Dynamic and Static SQL Support

This section describes the dynamic and static SQL support provided by Natural.

The following topics are covered:

Related Documentation


SQL Support - General Information

The SQL support of Natural combines the flexibility of dynamic SQL support with the high performance of static SQL support.

In contrast to static SQL support, the Natural dynamic SQL support does not require any special consideration with regard to the operation of the SQL interface. All SQL statements required to execute an application request are generated automatically and can be executed immediately with the Natural RUN command. Before executing a program, you can look at the generated SQLCODE, using the LISTSQL command.

Access to DB2 through Natural has the same form whether dynamic or static SQL support is used. Thus, with static SQL support, the same SQL statements in a Natural program can be executed in either dynamic or static mode. An SQL statement can be coded within a Natural program and, for testing purposes, it can be executed using dynamic SQL. If the test is successful, the SQL statement remains unchanged and static SQL for this program can be generated.

Thus, during application development, the programmer works in dynamic mode and all SQL statements are executed dynamically, whereas static SQL is only created for applications that have been transferred to production status.

Internal Handling of Dynamic Statements

Natural automatically provides for the preparation and execution of each SQL statement and handles the opening and closing of cursors used for scanning a table.

The following topics are covered:

I/O Module NDBIOMO for Dynamic SQL Statement Execution

As each dynamic execution of an SQL statement requires a statically defined DECLARE STATEMENT and DECLARE CURSOR statement, a special I/O module named NDBIOMO is provided which contains a fixed number of these statements and cursors. This number is specified during the generation of the NDBIOMO module in the course of the Natural for DB2 installation process.

Statement Table

If possible, an SQL statement is only prepared once and can then be executed several times if required. For this purpose, Natural internally maintains a table of all SQL statements that have been prepared and assigns each of these statements to a DECLAREd STATEMENT in the module NDBIOMO. In addition, this table maintains the cursors used by the SQL statements SELECT, FETCH, UPDATE (positioned) and DELETE (positioned).

Each SQL statement is uniquely identified by:

  • the name of the Natural program that contains this SQL statement,

  • the line number of the SQL statement in this program,

  • the name of the Natural library into which this program was stowed,

  • the time stamp when this program was stowed.

Once a statement has been prepared, it can be executed several times with different variable values, using the dynamic SQL statement EXECUTE USING DESCRIPTOR or OPEN CURSOR USING DESCRIPTOR.

When the full capacity of the statement table is reached, the entry for the next prepared statement overwrites the entry for a free statement whose latest execution is the least recent one.

When a new SELECT statement is requested, a free entry in the statement table with the corresponding cursor is assigned to it and all subsequent FETCH, UPDATE and DELETE statements referring to this SELECT statement will use this cursor. Upon completion of the sequential scanning of the table, the cursor is released and free for another assignment. While the cursor is open, the entry in the statement table is marked as used and cannot be reused by another statement.

If the number of nested FIND (SELECT) statements reaches the number of entries available in the statement table, any further SQL statement is rejected at execution time and a Natural error message is returned.

The size of the statement table depends on the size specified for the module NDBIOMO. Since the statement table is contained in the DB2 buffer area, the setting of Natural profile parameter DB2SIZE (see also Natural Parameter Modifications for Natural for DB2 in Installing Natural for DB2 on z/OS in the Installation documentation) may not be sufficient and may need to be increased.

Processing of SQL Statements Issued by Natural

The embedded SQL uses cursor logic to handle SELECT statements. The preparation and execution of a SELECT statement is done as follows:

  1. The typical SELECT statement is prepared by a program flow which contains the following embedded SQL statements (note that X and SQLOBJ are SQL variables, not program labels):

    DECLARE SQLOBJ STATEMENT
    DECLARE X CURSOR FOR SQLOBJ
    INCLUDE SQLDA (copy SQL control block)

    Then, the following statement is moved into SQLSOURCE:

    SELECT PERSONNEL_ID, NAME, AGE
     FROM EMPLOYEES
     WHERE NAME IN (?, ?)
        AND AGE BETWEEN ? AND ?

    Anmerkung:
    The question marks (?) above are parameter markers which indicate where values are to be inserted at execution time.

    PREPARE SQLOBJ FROM SQLSOURCE
  2. Then, the SELECT statement is executed as follows:

    OPEN X USING DESCRIPTOR SQLDA
    FETCH X USING DESCRIPTOR SQLDA

    The descriptor SQLDA is used to indicate a variable list of program areas. When the OPEN statement is executed, it contains the address, length and type of each value which replaces a parameter marker in the WHERE clause of the SELECT statement. When the FETCH statement is executed, it contains the address, length and type of all program areas which receive fields read from the table.

    When the FETCH statement is executed for the first time, it sets the Natural system variable *NUMBER to a non-zero value if at least one record is found that meets the search criteria. Then, all records satisfying the search criteria are read by repeated execution of the FETCH statement.

    To help improve performance, especially when using distributed databases, the DB2-specific FOR FETCH ONLY clause can be used. This clause is generated and executed if rows are to be retrieved only; that is, if no updating is to take place.

  3. Once all records have been read, the cursor is released by executing the following statement:

    CLOSE X

Preparing Programs for Static Execution

This section describes how to prepare Natural programs for static execution.

The following topics are covered:

For an explanation of the symbols used in this section to describe the syntax of Natural statements, see Syntax Symbols in the Statements documentation.

Basic Principles

Static SQL is generated in Natural batch mode for one or more Natural applications which can consist of one or more Natural object programs. The number of programs that can be modified for static execution in one run of the generation procedure is limited to 999.

During the generation procedure, the database access statements contained in the specified Natural objects are extracted, written to work files, and transformed into a temporary Assembler program. If no Natural program is found that contains SQL access or if any error occurs during static SQL generation, batch Natural terminates and condition code 40 is returned, which means that all further JCL steps must no longer be executed.

The Natural modules NDBCHNK and NDBSTAT must reside in a steplib of the generation step. Both are loaded dynamically during the execution of the generation step.

The temporary Assembler program is written to a temporary file (the Natural work file CMWKF06) and precompiled. The size of the workfile is proportional to the maximum number of programs, the number of SQL statements and the number of variables used in the SQL statements. During the precompilation step, a database request module (DBRM) is created, and after the precompilation step, the precompiler output is extracted from the Assembler program and written to the corresponding Natural objects, which means that the Natural objects are modified (prepared) for static execution. The temporary Assembler program is no longer used and deleted.

A static database request module is created by using either the sample job provided on the installation medium or an appropriate job created with the Create DBRM function.

Generation Procedure: CMD CREATE Command

The following topics are covered:

Generating Static SQL for Natural Programs

Beginn der AnweisungslisteTo generate static SQL for Natural programs

  1. Logon to the Natural system library SYSDB2.

    Since a new SYSDB2 library has been created when installing Natural for DB2, ensure that it contains all Predict interface programs necessary to run the static SQL generation. These programs are loaded into SYSDB2 at Predict installation time (see the relevant Predict product documentation).

  2. Specify the CMD CREATE command and the Natural input necessary for the static SQL generation process; the CMD CREATE command has the following syntax:

    CMD CREATE DBRM static-name USING using-clause
    {application-name,object-name,excluded-object}
    :
    :

    The generation procedure reads but does not modify the specified Natural objects. If one of the specified programs was not found or had no SQL access, return code 4 is returned at the end of the generation step.

Static Name

If the PREDICT DOCUMENTATION option is to be used, a corresponding Predict static SQL entry must be available and the static-name must correspond to the name of this entry. In addition, the static-name must correspond to the name of the DBRM to be created during precompilation. The static-name can be up to 8 characters long and must conform to Assembler naming conventions.

USING Clause

The using-clause specifies the Natural objects to be contained in the DBRM. These objects can either be specified explicitly as INPUT DATA in the JCL or obtained as PREDICT DOCUMENTATION from Predict.

INPUT DATA
PREDICT DOCUMENTATION

WITH XREF

YES
NO
FORCE

FS

OFF
ON

[LIB lib-name ]

DCTODP

OFF
ON

If the parameters to be specified do not fit in one line, specify the command identifier (CMD) and the various parameters in separate lines and use both the input delimiter (as specified with the Natural profile/session parameter ID - default is a comma (,) - and the continuation character indicator - as specified with the Natural profile/session parameter CF; default is a percent (%) - as shown in the following example:

Example:

CMD
CREATE,DBRM,static,USING,PREDICT,DOCUMENTATION,WITH,XREF,NO,%
LIB,library

Alternatively, you can also use abbreviations as shown in the following example:

Example:

CMD CRE DBRM static US IN DA W XR Y FS OFF LIB library

The sequence of the parameters USING, WITH, FS and LIB is optional.

INPUT DATA

As input data, the applications and names of the Natural objects to be included in the DBRM must be specified in the subsequent lines of the job stream ( application-name,object-name). A subset of these objects can also be excluded again (excluded-objects). Objects in libraries whose names begin with SYS can be used for static generation, too.

The applications and names of Natural objects must be separated by the input delimiter - as specified with the Natural profile parameter ID; default is a comma (,). If you wish to specify all objects whose names begin with a specific string of characters, use an object-name or excluded-objects name that ends with asterisk notation (*). To specify all objects in an application, use asterisk notation only.

Example:

LIB1,ABC*
  LIB2,A*,AB*
  LIB2,*
  :
  .

The specification of applications/objects must be terminated by a line that contains a period (.) only.

PREDICT DOCUMENTATION

Since Predict supports static SQL for DB2, you can also have Predict supply the input data for creating static SQL by using already existing PREDICT DOCUMENTATION.

WITH XREF Option

Since Predict Active References supports static SQL for DB2, the generated static DBRM can be documented in Predict, and the documentation can be used and updated with Natural.

WITH XREF is the option which enables you to store cross-reference data for a static SQL entry in Predict each time a static DBRM is created (YES). You can instead specify that no cross-reference data are stored (NO) or that a check is made to determine whether a Predict static SQL entry for this static DBRM already exists (FORCE). If so, cross-reference data are stored; if not, the creation of the static DBRM is not allowed. For more detailed information on Predict Active References, refer to the relevant Predict documentation.

When WITH XREF (YES/FORCE) is specified, XREF data are written for both the Predict static SQL entry (if defined in Predict) and each generated static Natural program. However, static generation with WITH XREF (YES/FORCE) is possible only if the corresponding Natural programs have been cataloged with XREF ON.

WITH XREF FORCE only applies to the USING INPUT DATA option.

Anmerkung:
If you do not use Predict, the XREF option must be omitted or set to NO and the module NATXRF2 need not be linked to the Natural nucleus.

FS Option

If the FS (file server) option is set to ON, a second SELECT is generated for the Natural file server for DB2. ON is the default setting.

If the FS option is set to OFF, no second SELECT is generated, which results in less SQL statements being generated in your static DBRM and thus in a smaller DBRM.

LIB Option

With the LIB (library) option, a Predict library other than the default library (*SYSSTA*) can be specified to contain the Predict static SQL entry and XREF data. The name of the library can be up to eight characters long.

DCTODP Option

The DCTODP option is only relevant if you are doing a static generation for programs which have been catalogued with Natural parameter DC=’,’.

By the DCTODP parameter it can be determined whether the static generation will change decimal literals in SQL statements by replacing the decimal character comma ‘,’ by the decimal character period ‘.’ in the generated static SQL assembler program. This will be necessary since the DB2 precompiler does not support decimal point comma in decimal literals.

When DCTODP OFF is specified no conversion of decimal point comma to decimal point period will take place. DCTODP OFF is the default value.

When DCTODP ON is specified static generation will convert decimal point comma to decimal point period.

If DCTODP ON is used, you should be sure your programs are coded unambiguously when using the comma as separator in function calls and various SQL clauses like IN or ORDER BY so that the comma as separator in element lists can’t be misinterpreted as decimal point of a decimal literal

For instance, if you code a SQL IN clause while using DC=’,’ like

Column-name IN (10,20,30,40).

Static generation with DCTODP ON change the IN clause to

Column-name IN (10,20 , 30,40).

IN list contains two values 10.20 and 30.40.

The same IN clause in static generation with DCTODP OFF (default value) will be changed to

Column-name IN (10,20 , 30,40).

IN list contains four values 10 , 20 , 30 and 40.

If you had coded

Column-name IN (10 , 20 , 30 , 40).

Static generation will always generate the IN clause with DCTODP either ON or OFF to

Column-name IN (10 , 20 , 30 , 40).

Precompilation of the Generated Assembler Program

In this step, the precompiler is invoked to precompile the generated temporary Assembler program. The precompiler output consists of the DBRM and a precompiled temporary Assembler program which contains all the database access statements transformed from SQL into Assembler statements.

Later, the DBRM serves as input for the BIND step and the Assembler program as input for the modification step.

Modification Procedure: CMD MODIFY Command

The modification procedure modifies the Natural objects involved by writing precompiler information into the object and by marking the object header with the static-name as specified with the CMD CREATE command.

In addition, any existing copies of these objects in the Natural global buffer pool (if available) are deleted and XREF data are written to Predict (if specified during the generation procedure).

Beginn der AnweisungslisteTo perform the modification procedure

  1. Logon to the Natural system library SYSDB2.

  2. Specify the CMD MODIFY command which has the following syntax:

    CMD MODIFY [XREF]

The input for the modify step is the precompiler output which must reside on a data set defined as the Natural work file CMWKF01.

The output consists of precompiler information which is written to the corresponding Natural objects. In addition, a message is returned telling you whether it was the first time an object was modified for static execution (modified) or whether it had been modified before (re-modified).

Assembler/Natural Cross-References

If you specify the XREF option of the CMD MODIFY command, an output listing is created on the work file CMWKF02, which contains the DBRM name and the Assembler statement number of each statically generated SQL statement together with the corresponding Natural source code line number, program name, library name, database ID and file number.

  -------------------------------------------------------------------------....
    DBRMNAME STMTNO      LINE NATPROG  NATLIB   DB  FNR COMMENT            ....
  -------------------------------------------------------------------------....
    TESTDBRM 000627      0390 TESTPROG SAG      010 042 INSERT             ....
             000641      0430                           INSERT             ....
             000652      0510                           SELECT             ....
             000674      0570                           SELECT             ....
             000698      0570                           SELECT      2ND    ....
             000728      0650                           UPD/DEL            ....
             000738      0650                           UPD/DEL     2ND    ....
             000751      0700                           SELECT             ....
             000775      0700                           SELECT      2ND    ....

The columns in the output listing are explained below:

Column Explanation
DBRMNAME Name of the DBRM which contains the static SQL statement.
STMTNO Assembler statement number of the static SQL statement.
LINE Corresponding Natural source code line number.
NATPROG Name of the Natural program that contains the static SQL statement.
NATLIB Name of the Natural library that contains the Natural program.
DB / FNR Natural database ID and file number.
COMMENT Type of SQL statement, where 2ND indicates that the corresponding statement is used for a reselection; see also the Concept of the File Server.

BIND of the Precompiled DBRM

We recommend that you execute the DB2 BIND command after the CMD MODIFY command.

The DB2 BIND command binds the DBRM into a DB2 package. You can bind one or more DB2 packages into a DB2 application plan. In addition to the packages of static DBRMs created with the CMD CREATE command, this application plan can also contain the package of the DBRM of the NDBIOMO module Natural provides for dynamic SQL execution.

A DBRM can be bound into any number of packages and the packages can be bound into any number of application plans where required. A plan is physically independent of the environment where the program is to be run. However, you can group your packages logically into plans which are to be used for either batch or online processing, where the same package can be part of both a batch plan and an online plan.

Unless you are using plan switching, only one plan can be executed per Natural session. Thus, you must ensure that the plan name specified in the BIND step is the same as the one used to execute Natural.

Execution of Natural in Static Mode

To be able to execute Natural in static mode, all users of Natural must have the DB2 EXECUTE PLAN/PACKAGE privilege for the plan created in the BIND step.

To execute static SQL, start Natural and execute the corresponding Natural program. Internally, the Natural runtime interface evaluates the precompiler data written to the Natural object and then performs the static accesses.

To the user there is no difference between dynamic and static execution.

Mixed Dynamic/Static Mode

It is possible to operate Natural in a mixed static and dynamic mode where for some programs static SQL is generated and for some not.

The mode in which a program is run is determined by the Natural object program itself. If a static DBRM is referenced in the executing program, all statements in this program are executed in static mode.

Anmerkung:
Natural programs which return a runtime error do not automatically execute in dynamic mode. Instead, either the error must be corrected or, as a temporary solution, the Natural program must be recataloged to be able to execute in dynamic mode.

Within the same Natural session, static and dynamic programs can be mixed without any further specifications. The decision which mode to use is made by each individual Natural program.

Messages and Codes

For a list of error messages that may be issued during static generation, refer to Static Generation Messages and Codes Issued under NDB in the Natural Messages and Codes documentation.

Application Plan Switching

This section describes how to switch application plans within the same Natural session in different TP-monitor environments or in batch mode.

The following topics are covered:

Basic Principles of Plan Switching

When using application plan switching, you can switch to a different application plan within the same Natural session.

If a second application plan is to be used, this can be specified by executing the Natural program NATPLAN. NATPLAN is contained in the Natural system library SYSDB2 and can be invoked either from within a Natural program or dynamically by entering the command NATPLAN at the NEXT prompt. The only input value required for NATPLAN is an eight-character plan name. If no plan name is specified, you are prompted by the system to do so.

Before executing NATPLAN, ensure that any open DB2 recovery units are closed.

Since the NATPLAN program is also provided in source form, user-written plan switching programs can be created using similar logic.

The actual switch from one plan to another differs in the various environments supported. The feature is available under Com-plete, CICS, and IMS TM MPP. When using the Call Attachment Facility (CAF) or Resource Recovery Services Attachment Facility (RRSAF), it is also available in TSO and batch environments.

In some of these environments, a transaction ID or code must be specified instead of a plan name.

Plan Switching under CICS

Under CICS, you have the option of using either plan switching by transaction ID (default) or dynamic plan selection exit routines. Thus, by setting the field #SWITCH-BY- TRANSACTION-ID in the NATPLAN program to either TRUE or FALSE, either the subroutine CMTRNSET or the desired plan name is written to temporary storage queue.

For more information on activating plan switching under CICS, see Installation Steps Specific to CICS in the Installing Natural for DB2 on z/OS documentation.

Below is information on:

Plan Switching by CICS/DB2 Exit Routine

If #SWITCH-BY-TRANSACTION-ID is set to FALSE, the desired plan name is written to a temporary storage queue for a CICS/DB2 exit routine specified as PLANExit attribute of a DB2ENTRY or of the DB2CONN definition, the NATPLAN program must be invoked before the first DB2 access. Natural for DB2 provides NDBUEXT as CICS DB2 plan selection exit program. For additional information on CICS/DB2 exit routines, refer to the relevant IBM literature.

The name of the temporary storage queue is PLANsssstttt, where ssss is the remote or local CICS system identifier and tttt the CICS terminal identifier.

When running in a CICSplex environment, the CICS temporary storage queue PLANsssstttt containing the plan name must be defined with TYPE=SHARED or TYPE=REMOTE in a CICS TST.

For each new DB2 unit of recovery, the appropriate plan selection exit routine is automatically invoked. This exit routine reads the temporary storage record and uses the contained plan name for plan selection.

When no temporary storage record exists for the Natural session, a default plan name, contained in the plan exit, can be used. If no plan name is specified by the exit, the name of the plan used is the same as the name of the static program (DBRM) issuing the SQL call. If no such plan name exists, an SQL error results.

Plan Switching under Com-plete

In Com-plete environments, plan switching is accomplished by using the Call Attachment Facility (CAF), which releases the thread in use and attaches another one that has a different plan name.

Once the DB2 connection has been established, the same plan name continues to be used until the plan is explicitly changed with IBM's call attachment language interface (DSNALI). For additional information on the CAF interface, refer to the relevant IBM literature.

Under Com-plete, the NATPLAN program first issues an END TRANSACTION statement and then invokes an Assembler routine by using DB2SERV.

The assembler routine performs the actual switching. It issues a CLOSE request to DSNALI to terminate the DB2 connection (if one exists). It then issues an OPEN request to re-establish the DB2 connection and to allocate the resources needed to execute the specified plan.

If NATPLAN has not been executed before the first SQL call, the default plan used is the one defined in the Com-plete startup parameters. Once a plan has been changed using NDBPLAN, it remains scheduled until another plan is scheduled by NDBPLAN or until the end of the Natural session.

Plan Switching under IMS TM

In an IMS MPP environment, the switch is accomplished by using direct or deferred message switching. As a different application plan is associated with each IMS application program, message switching from one transaction code to another automatically switches the application plan being used.

Since Natural applications can perform direct or deferred message switches by calling the appropriate supplied routines, use of the NATPLAN program for plan switching is optional.

NATPLAN calls the Assembler routine CMDEFSW, which sets the new transaction code to be used with the next following terminal I/O operation.

Plan Switching under TSO and in Batch Mode

In the TSO and batch environments, plan switching is accomplished by using the Call Attachment Facility (CAF) or the Resource Recovery Services Attachment Facility (RRSAF). Either facility releases the thread in use and attaches another one that has a different plan name.

Below is information on:

Plan Selection with CAF

Initial connection and plan setting can be done using the subparameters DB2PLAN and DB2SSID of the NTDB2 macro or of the DB2 profile parameter without using the NATPLAN program. However, the initial settings could be overwritten by using the NATPLAN program.

When using the Call Attachment Facility (CAF), plan selection is either implicit or explicit. If no DB2 connection has been made before the first SQL call, a plan name is selected by DB2. If so, the plan name used is the same as the name of the program (DBRM) issuing the SQL call.

Once the DB2 connection has been established, the plan name is retained until explicitly changed by IBM's call attachment language interface (DSNALI). For additional information on the CAF interface, refer to the relevant IBM literature.

Under TSO and in batch mode, the NATPLAN program first issues an END TRANSACTION statement and then invokes an Assembler routine by using DB2SERV.

Anmerkung:
Modify the NATPLAN program by setting the #SSM field to the current DB2 subsystem name; the default name is DB2.

The assembler routine performs the actual switching. It issues a CLOSE request to DSNALI to terminate a possible DB2 connection. It then issues an OPEN request to re-establish the DB2 connection and to allocate the resources needed to execute the specified plan.

If NATPLAN has not been executed before the first SQL call, plan selection is done by DSNALI. If so, the plan name used is the same as the name of the program issuing the SQL call. The subsystem ID used is the one specified during the DB2 installation. If no such plan name or subsystem ID exists, a Natural error message is returned.

If a static DBRM issues the SQL call, a plan name must exist with the same name as the one of the static DBRM.

If dynamic SQL is used, a DB2 plan must exist which contains a package with the DBRM of the NDBIOMO module. If the name of the DB2 plan has neither been defined in the NATPLAN program nor with the DB2PLAN keyword subparameter, the DB2 Call Attachment Facility (CAF) uses the name of the NDBIOMO DBRM as the default plan name.

Anmerkung:
To avoid any confusion concerning the chosen plan name and/or subsystem ID, always call NATPLAN before the first SQL call.

Plan Selection with RRSAF

Initial connection and plan setting can be done using the keyword subparameters DB2COLL, DB2GROV, DB2PLAN, DB2SSID and DB2XID of the NTDB2 macro or of the DB2 profile parameter without using the NATPLAN program. However, the initial settings can be overwritten by using the NATPLAN program.

When using the Resource Recovery Services Attachment Facility (RRSAF), plan selection is explicit.

RRSAF is used if IBM's DSNRLI interface module is linked to Natural. Once the DB2 connection has been established, the plan name is retained until explicitly changed with RRSAF. For additional information on RRSAF, refer to the relevant IBM literature.

The NATPLAN program performs the actual switching. It issues a TERMINATE IDENTIFY request to DSNRLI to terminate a possible DB2 connection. NATPLAN then issues an IDENTIFY request to re-establish the DB2 connection. This request is followed by SIGNON and CREATE THREAD requests.

In an RRSAF environment, up to four of the following parameters can be specified in NATPLAN where #PLAN is mandatory:

Parameter Default Value Format Explanation
#PLAN None A8 Name of the plan used for SQL processing in the thread created (CREATE THREAD).
#SSM DB2 A4 Subsystem ID of the DB2 server connected (IDENTIFY).
#COLLID COLLID A18

Only used if the first character of #PLAN is a question mark (?).

Collection ID used for SQL processing in the thread created (CREATE THREAD).

#XID 1 I4

Indicates that a global transaction ID is used.

If set to 0 (SIGNON), no global transaction ID is used.

Example of Plan Selection with RRSAF under TSO

The example below demonstrates plan selection under TSO by using RRSAF.

NATPLAN
<Enter>
Please enter new plan name  NDBPLAN4
            ,SUB SYSTEM ID DB27
            ,COLLECTION ID
         ,global XID (0/1) __________1
<Enter>

Example of Plan Selection with RRSAF in Batch Mode

The example below demonstrates plan selection in batch mode by using RRSAF:

NATPLAN NDBPLAN4,DB27, ,1