Customizing Natural for VSAM

The Natural parameters in a VSAM environment are defined in one location:

  • the Natural standard parameters, contained in the Natural parameter module; see Building a Natural Parameter Module in the Operations documentation,

  • the Natural parameters specific to VSAM, also contained in the Natural parameter module; see parameter macro NTVSAM in the Parameter Reference documentation.

The Natural parameter module can be edited to conform to your site standards, and then assembled and linked using the appropriate jobs (see Installing Natural for VSAM in the Installation for z/OS documentation).

This section covers the following topics:

Customizing the Natural Parameter Module

To be able to run Natural in a VSAM environment, you must include the profile parameter VSIZE, the NTDB and the NTVSAM macro in your Natural parameter module (see the section Installing Natural for VSAM in the Installation for z/OS documentation).

For an Adabas system file:

VSIZE=72,
NTDB VSAM,vsam-dbid
NTVSAM

For a VSAM system file:

VSIZE=160,
  
FNAT=(vsam-dbid,fnr,dd-name),
FUSER=(vsam-dbid,fnr,dd-name),
FDIC=(vsam-dbid,fnr,dd-name),
FSPOOL=(vsam-dbid,fnr,dd-name),
FSEC=(vsam-dbid,fnr,dd-name)
  
NTDB VSAM,vsam-dbid
NTVSAM ... SFILE=ON,...

dd-name is the logical name (DD or DLBL) of the system file; see also Installing Natural for VSAM in the Installation for z/OS documentation.

Note:
If you use VSAM system files with Natural ISPF, see also the Natural ISPF documentation.

Below is information on:

VSIZE Parameter

VSIZE is a Natural profile parameter which can also be specified dynamically. It is used to specify the size of the Natural buffer area for VSAM and defines the maximum memory usage for the internal tables of the Natural interface to VSAM; the actual sizes of these tables depend on the values set in the Natural parameter module (see Assembling the VSAM-specific Natural Parameter Module).

Possible values are 0, 1 - 512 KB.

If you use the default values specified in the Natural parameter module, the value of the VSIZE parameter must be at least 72 KB.

If VSIZE is set to 0, Natural for VSAM is not available and a corresponding error message is returned when trying to access VSAM files. Disabling Natural for VSAM leads to slight performance improvements because of skipping the initialization, relocation and roll efforts of the Natural interface to VSAM.

NTDB Macro

The NTDB macro is used to specify the database numbers that relate to VSAM files; that is, the logical assignments available for Natural.

The value range of NTDB parameters is described in the Natural Parameter Reference documentation.

Note:
Ensure that the DBIDs selected in the NTDB macro for VSAM do not conflict with DBIDs selected for other database management systems.

NTVSAM Macro

The NTVSAM macro is used to specify the VSAM specific parameters.

The value range of the NTVSAM keyword subparameters is described in the Natural Parameter Reference documentation

Assembling the VSAM-specific Natural Parameter Module

If the default values supplied in the Natural parameter module do not meet your requirements, you can change the parameter values to suit your environment. The individual VSAM-specific parameters contained in the Natural parameter module are described in the following section.

The VSAM-specific Natural parameter module is created by assembling the macro NTVSAM.

Optionally, one or more of the following macros:

If more than one macro is specified, the NTVSAM macro must be specified first; further macros after the NTVSAM macro can be specified in any order.

Natural I/O Modules for VSAM

The Natural I/O module for VSAM depends on the actual environment in use.

All available I/O modules are delivered in source form so you can make site-specific modifications and use environment-specific macros and/or precompilers. The I/O module must be linked to the Natural parameter module.

The I/O modules available are:

NVSCICS Module

The NVSCICS module is required for CICS under z/OS. The module contains the following parameter:

&FCTRELI - Indicator of Reliable Remote FCT Entries

The &FCTRELI parameter indicates whether the key length and record size of a remote file are correctly defined in the FCT entry of the Application Owning Region (AOR).

Possible values Default value
0 or 1 0

When this parameter is set to 1, NVSCICS assumes a correct FCT entry.

When this parameter is set to 0, NVSCICS issues dummy commands to force opening of the file in the File Owning Region (FOR) region and then repeats inquiring for the real values.

If the FCT entry does not contain a key length definition, NVSCICS uses the key length of the corresponding VSAM DDM.

NVSMISC Module

The NVSMISC module is required in all environments except for CICS. The module mainly consists of the NVMMISC macro, which is used to generate the NVSMISC I/O interface according to your operating system and/or TP-monitor environment.

NVSMISC is specified as follows:

name NVMMISC NONRLS=value TIMEOUT=value DSECTS=value DEFER=value COMMIT=value ERROR=value HFACTOR=value READINT=value SMARTS=value TVS=value

The name of the relocatable module must be 8 characters long.

The individual parameters are described in the following section; specify these parameters according to your requirements.

NONRLS - Switch from RLS to Non-RLS Mode

When Natural for VSAM issues an RLS-OPEN for an RLS file and this file has already been opened in non-RLS mode in this z/OS session, this parameter specifies whether Natural for VSAM issues an open retry in a non-RLS mode, or whether an open error occurs.

Possible values Default value
YES/NO YES

TIMEOUT - Timeout in Seconds for an RLS Request

This parameter specifies the time in seconds Natural for VSAM is waiting to obtain a lock on a Natural for VSAM record when a lock on the record is already held by another user. For further details refer to the latest version of IBM manual z/OS DFSMS Macro Instructions for Data Sets.

Possible values Default value
0 - 10 0

DEFER - Defer Writes in LSR Pools

This parameter only applies in batch mode and under TSO.

This parameter specifies whether write operations to disk are to be deferred in the LSR pool. If so and if the LSR pool becomes full, Natural for VSAM writes to disk those 5% of the pool area which have not been used for the longest time.

Possible values Default value
YES/NO NO

DSECTS - List VSAM System DSECTs

The DSECTS parameter specifies whether the VSAM system DSECTs are to be listed or not.

Possible values Default value
YES/NO NO

COMMIT - Support of Buffer Flush for LSR Pools

This parameter only applies in batch mode and under TSO.

The COMMIT parameter specifies whether all non-committed updates in any LSR pool are to be written to disk with each END TRANSACTION statement of a user program.

Possible values Default value
YES/NO NO

Note:
The specification of COMMIT=YES increases the I/O rate considerably.

ERROR - Issue Initialization Error

This parameter issues a Natural initialization error if any DD or DLBL card is omitted in the runtime JCL (see also the macro NTVLSR).

Possible values Default value
YES/NO YES

If set to NO, processing is continued and Natural for VSAM will be initialized.

HFACTOR - Factor for Hiperspace Buffers

The HFACTOR parameter specifies a factor for the creation of ESO Hiperspace buffers. When initializing such a Hiperspace, the corresponding BLDVRP request may lead to a Natural error message, in which case the value of HFACTOR must be reduced.

Possible values Default value
0 - a value where a corresponding Natural error message is returned 100

READINT - Read Integrity for Upgrade Set

The READINT parameter specifies whether read integrity for an upgrade set should be granted or not.

Possible values Default value
YES/NO NO

SMARTS - Support of SMARTS and Com-plete

The SMARTS parameter is required if installing Natural for VSAM under SMARTS and/or in a Complete environment.

Possible values Default value
YES/NO NO

TVS - Support of DFSMS Transactional VSAM Services (DFSMStvs)

The TVS parameter specifies the support of DFSMStvs.

Possible values Default value
YES/NO NO