Natural Roll Server Operation

This section covers the following topics:

See also Natural Roll Server Functionality.

Roll Server System Requirements

This section describes the Roll Server system requirements.

APF Authorization

Link the module NATRSMvr (vr represents the relevant product version) to an Authorized Program Facility (APF) library, specifying IEWL parameter AC(1). Refer to Installing Natural on z/OS.

System Linkage Index

As the Roll Server reserves one system linkage index (System LX), check whether there is a high enough value of NSYSLX in member IEASYSxx of library SYS1.PARMLIB.

When the Roll Server terminates, its address space ID is no longer available because a System LX has been used. It becomes available again with the next IPL.

Once a System LX has been reserved, it is reused with every restart of the Roll Server until the next IPL.

CF Structure

A CF structure is used to hold the roll file directory in a z/OS Parallel Sysplex environment.

XCF Signaling Paths

In a z/OS Parallel Sysplex environment, the Roll Servers communicate via the XCF Signaling Services. As the default XCF group name, the leftmost eight bytes of the CF structure name are used.

If you want to specify your own XCF group name, use the NATRSU24 user exit. For more information on this user exit, see NATRSU24 User Exit.

Formatting the Roll File

You can define a roll file either as a physical sequential (PS) data set or as a VSAM linear file.

Beginn der AnweisungslisteTo format a roll file

  1. Allocate the roll file as a PS data set with a fixed record format.

    Oder:
    Use the IDCAMS utility to define a VSAM linear file (see also Example of an IDCAMS Job).

  2. Format the roll file by using the module NATRSRFI.

    Anmerkung:
    If you plan to use the roll file of a previous version, it is sufficient to execute the NATRSRFI RESET function.

    During formatting, the PS data set is converted to a BDAM (basic direct access method) data set with a device-dependent block size. The block size of a VSAM file is equal to the control interval size defined by IDCAMS.

  3. If the roll server executes in a z/OS Parallel Sysplex environment, reset the Coupling Facility structure as described in the Notes Concerning the Formatting or Resetting of Roll Files.

  4. Enter the following parameter string under the DD name RFIPARMS or as PARM on the JCL EXEC statement:

    function,dd-name,slot-size,number-of-slots

    All parameters are positional; they are explained in the following table:

    Parameter Description
    function FORMAT Format the roll file.
    RESET

    All roll file slots are reset (marked as free). You can only use this parameter value if the roll file has already been formatted.

    The only other parameter allowed is dd-name.

    LIST

    Print a list of session IDs contained in the roll file and their last activity.

    The only other parameter allowed is dd-name.

    dd-name The name of the DD statement under which the roll file has been specified.
    slot-size

    The size of a roll file slot in bytes. This size is rounded to the next higher multiple of the block size used.

    It is recommended to initially use a slot size equal to the size of the Natural thread. Then look at the Roll Server statistics. They also show the largest occurrence of a thread size. Use this value to reduce the slot size, if necessary.

    number-of-slots

    The number of roll file slots to be allocated. This number is the maximum number of concurrently active users.

    This parameter is optional. If omitted, the entire roll file, as allocated, will be formatted.

    Note that during formatting, the system abend code SB37 or SD37 (or S209 for a VSAM file) can be encountered. This abend is intercepted by the formatting routine and can be ignored.

    To calculate the required disk space in cylinders for a roll file (SPACE parameter of the DD statement), use the following formula: 

    number-of-cylinders = ceiling (number-of-slots * slot-size / (30*block-size))

    or in tracks

    number-of-tracks = ceiling (number-of-slots * slot-size / (2*block-size))

    The block size used is:

    23476 for 3380 DASD

    27998 for 3390 DASD

    22928 for 9345 DASD

    CI size of the VSAM roll file

    In addition, space is needed for the roll file directory header (40 bytes) and one directory entry for each roll file slot (24 bytes). Thus, one additional block is needed for roughly 976 slots on 3380, 1164 slots on 3390, or 953 slots on 9345 DASD.

Example of an IDCAMS Job

The following is an example of an IDCAMS job used to define a VSAM roll file: 

//FBDEFINE JOB  (FB,117),FB,CLASS=K,MSGCLASS=X,NOTIFY=FB
//IDCAMS EXEC  PGM=IDCAMS                              
//SYSPRINT DD  SYSOUT=X                                
//SYSIN    DD  *                                       
        DELETE FB.VSAM.LINEAR                          
        DEFINE CLUSTER (NAME(FB.VSAM.LINEAR)  -        
        LINEAR                                -        
        REUSE                                 -        
        CONTROLINTERVALSIZE(12388)            -        
        CYLINDERS(50,0)                       -        
        SHAREOPTIONS(4 4))                    -        
        DATA (NAME(FB.VSAM.LINEAR.DATA))               
/*                                                     
//

NATRSRFI Output

If a DD statement with ddname RFIPRINT is specified, NATRSRFI directs its output to this data set. When RFIPRINT is omitted, output is written to JESMSGLG using the WTO macro (ROUTDCE=11). Note that RFIPRINT must be specified for the LIST function.

NATRSRFI Condition and Abend Codes:

The following condition codes are used:

Code Explanation
0 Normal completion.
4 Number of slots formatted is less than requested.
20 Parameter error.

The following user abend codes are used:

Abend Code Cause
U0100 Open for RFIPARMS or RFIPRINT failed.
U0101 Open for roll file failed.
U0102 VSAM PUT failed.
U0103 VSAM GET failed.

Examples:

Example 1: 

//FBRUNRFI JOB  (FB,218),FB,CLASS=K,MSGCLASS=X,NOTIFY=FB                        
//FORMAT   EXEC PGM=NATRSRFI                                                    
//STEPLIB  DD  DISP=SHR,DSN=NATURAL.NAT85.LOAD                                  
//RF1      DD  DISP=SHR,DSN=FB.SYSF.ROLLF1                                      
//RF2      DD  DISP=SHR,DSN=FB.VSAM.LINEAR                                      
//RFIPARMS DD  *                                                                
FORMAT,RF1,200000,1000                                                          
FORMAT,RF2,200000

Excerpt from resulting JESMSGLG: 

+FBRUNRFI: FORMAT,RF1,200000,1000
+FBRUNRFI: RF1: FB.SYSF.ROLLF1
+FBRUNRFI:      Creation date: 2016/06/08 Volume: ADA002(3390)
IEC031I D37-04,IFG0554P,FBRUNRFI,FORMAT,RF1,305B,ADA002,FB.SYSF.ROLLF1
+FBRUNRFI: Not enough space for 1000 slots.
+FBRUNRFI:       60 Blocks written. Block size is 27998.
+FBRUNRFI:        1 Directory block.
+FBRUNRFI:        8 Blocks per slot. Slot size is 223984.
+FBRUNRFI:        7 Slots initialized. Roll file version 911.
+FBRUNRFI:        3 Blocks unused.
+FBRUNRFI: FORMAT,RF2,200000
+FBRUNRFI: RF2: FB.VSAM.LINEAR
+FBRUNRFI:      Creation date: 2016/06/08 Volume: FSMS04(VSAM)
IEC070I 209-220,FBFORMAT,RUN1,ROLLF1,4A04,FSMS04,FB.VSAM.LINEAR,  277
IEC070I FB.VSAM.LINEAR.DATA,UCAT.USER1                      
+FBRUNRFI:     2835 Blocks written. Block size is 16384.
+FBRUNRFI:        1 Directory block.
+FBRUNRFI:       13 Blocks per slot. Slot size is 212992.
+FBRUNRFI:      218 Slots initialized. Roll file version 911.

Example 2: 

//FBRUNRFI JOB  (FB,218),FB,CLASS=K,MSGCLASS=X,NOTIFY=FB
//FORMAT   EXEC PGM=NATRSRFI,PARM='FORMAT,RF1,200000'
//STEPLIB  DD  DISP=SHR,DSN=NATURAL.NAT85.LOAD
//RF1      DD  DISP=SHR,DSN=FB.SYSF.ROLLF1
//RFIPRINT DD  SYSOUT=X

Resulting RFIPRINT: 

Natural Roll Server - Roll File Utility Version 
851
FORMAT,RF1,200000
RF1: FB.SYSF.ROLLF1
Creation date: 2016/06/08 Volume: ADA002(3390)
60 Blocks written. Block size is 27998.
1 Directory block.
8 Blocks per slot. Slot size is 223984.
7 Slots initialized. Roll file version 911.
3 Blocks unused.

Notes Concerning the Formatting or Resetting of Roll Files

  • You can format or reset several roll files at once by specifying several parameter lines in RFIPARMS.

  • You cannot format or reset a roll file while the roll server is active.

  • When the roll file is formatted in a z/OS Parallel Sysplex environment, the roll server Coupling Facility structure must also be cleared using the SETXCF operator command, for example: 

    SETXCF FORCE,STR,STRNAME=NATROLL1

Starting the Roll Server

You start the Roll Server either as a batch job or as a started task by executing module NATRSMvr (where vr represents the relevant product version). The roll file(s) must be defined as DD statements with ddname ROLLF1 to ROLLF5.

You can specify parameters in the JCL EXEC statement, in a parameter file, or in both. A parameter specified in the EXEC statement overwrites the corresponding parameter in the parameter file.

Software AG recommends using a parameter file. The parameter TIMEOUTREPEAT (see Parameters in the Parameter File) and future parameters can only be specified in the parameter file. Existing JCL will continue to execute unchanged.

This section covers the following topics:

Parameters in the JCL EXEC Statement

Parameters in the JCL EXEC statement: 

subsystem-id,number-of-roll-files,number-of-LRB-slots,LRB-slot-size,CF-structure-name,low-water-mark,high-water-mark,non-activity-time,timeout-check-time,message-case

All parameters are positional and must be separated by a comma. They are explained in the table below:

Parameter Possible Values Default Comment
subsystem-id 4-byte non-blank string NATv The specified value must match the value of the Natural profile parameter SUBSID (v = version number).

Anmerkung:
With Natural under CICS, refer to the ROLLSRV parameter in the NCMDIR macro for setting the appropriate subsystem ID.

number-of-roll-files 0 - 5 1 In a z/OS non-Parallel Sysplex environment, the Roll Server can operate without a roll file, using only the in-storage Local Roll Buffer.
number-of-LRB-slots 1 - 32767 none The number of LRB slots assigned for each roll file in use.

(The total number of LRB slots is calculated by this formula:
number-of-roll-files * number-of-LRB-slots)

LRB-slot-size any numeric value roll file slot size Value in number of bytes.

This parameter must be specified if no roll file is used.

If roll files are used, this parameter is ignored and the roll file slot size is used instead.

If no roll files are used meaning the number-of-roll-files is zero, this parameter is mandatory.

CF-structure-name any valid structure name none If you specify less than 16 characters, blanks are appended.

Only specify this parameter if you use the Coupling Facility (with z/OS Parallel Sysplex).

low-water-mark 0 - 9

7
(single z/OS)

0
(Sysplex)

Specifies the low water mark in steps of 10 percent of the number of LRB slots.
high-water-mark 0 - 10

8
(single z/OS)

0
(Sysplex)

Analogous to low-water-mark parameter.

A value of 10 means that the staging task will never be activated. It is only recommended to specify 10 if the LRB is large enough to serve all simultaneously active Natural sessions.

non-activity-time 1 - 999999 none Number of hours a session can be inactive before it is deleted from the roll file.

If this time is exceeded, the session is deleted during the next scheduled timeout check.

If this parameter is omitted, no timeout check will be executed.

This parameter can be changed using operator command TIMEOUT (see Operating the Roll Server).

timeout-check-time 0000 - 2359 none The time of day that the timeout check is to be run.

Sessions will be deleted if they have been inactive longer than the non-activity time specified by the preceding parameter.

If this parameter is omitted, no timeout check will be scheduled.

This parameter can be changed using the operator command TIMEOUT (see Operating the Roll Server).

message-case UCTRAN or blank blank Specify UCTRAN if the Roll Server is to issue all its messages in upper case.

Parameters in the Parameter File

The parameter file is a physical sequential file (DSORG=PS). In your JCL, specify this file with DDNAME RSMPARM.

Parameters in the parameter file are specified as name=value pairs, for example, NUMFILES=1. Specify one parameter per line, starting in Column 1. The name=value pair is terminated by the first blank, and the rest of the line is not examined. Lines starting with an asterisk (*) in Column 1 are treated as comments. Parameters are translated to upper case before they are processed.

Parameter Possible Values Default Comment
SUBSID 4-byte non-blank string NATv The specified value must match the value of the Natural profile parameter SUBSID (v = version number).

Anmerkung:
With Natural under CICS, refer to the CICSPLX parameter in the NCMDIR macro for setting the appropriate subsystem ID.

NUMFILES 0 - 5 1 In a z/OS non-Parallel Sysplex environment, the Roll Server can operate without a roll file, using only the in-storage Local Roll Buffer.
NUMSLOTS 1 - 32767 none The number of LRB slots assigned for each roll file in use.

(The total number of LRB slots is calculated by this formula:
NUMFILES * NUMSLOTS)

SLOTSIZE any numeric value roll file slot size Value in number of bytes.

This parameter must be specified if no roll file is used.

If roll files are used, this parameter is ignored and the roll file slot size is used instead.

STRUCTURE any valid structure name none If you specify less than 16 characters, blanks are appended.

Only specify this parameter if you use the Coupling Facility (with z/OS Parallel Sysplex).

LOWWATER 0 - 9

7
(single z/OS)

0
(Sysplex)

Specifies the low water mark in steps of 10 percent of the number of LRB slots.
HIGHWATER 0 - 10

8
(single z/OS)

0
(Sysplex)

Analogous to low-water-mark parameter.

A value of 10 means that the staging task will never be activated. It is only recommended to specify 10 if the LRB is large enough to serve all simultaneously active Natural sessions.

NONACTIVITY 1 - 999999 none Number of hours a session can be inactive before it is deleted from the roll file.

If this time is exceeded, the session is deleted during the next scheduled timeout check.

If this parameter is omitted, no timeout check will be executed.

This parameter can be changed using the operator command TIMEOUT, (see Operating the Roll Server).

TIMEOUTCHECK 0000 - 2359 none The time of day that the timeout check is to be run.

Sessions will be deleted if they have been inactive longer than the non-activity time specified by the preceding parameter.

If this parameter is omitted, no timeout check will be scheduled.

This parameter can be changed using operator command TIMEOUT (see Operating the Roll Server).

TIMEOUTREPEAT 0 - 1440 none The number of minutes between timeout checks.

The first timeout check after Roll Server start is run after TIMEOUTREPEAT minutes.

If TIMEOUTCHECK is also specified, the first timeout check is run at the time specified with TIMEOUTCHECK, and then every TIMEOUTREPEAT minutes.

Specifying 0 or 1440 indicates no timeout repeat, and the timeout check is run only at the time specified with TIMEOUTCHECK.

MSGCASE UPPER or MIXED mixed case MSGCASE=UPPER causes all messages to be displayed in uppercase letters.

MSGCASE=MIXED causes all messages to be displayed in mixed case letters.

Anmerkung:
The Local Roll Buffer resides in a Memory Object "above the bar". Use the MEMLIMIT parameter on the EXEC statement to ensure enough memory can be allocated "above the bar".

Examples for Starting the Roll Server as a Batch Job

In the following examples, vr represents the relevant product version. 

//   EXEC PGM=NATRSMvr,PARM='NAvr,,1000'
//ROLLF1 DD DSN=SYSF.ROLLFILE

The subsystem ID is NAvr, one roll file is used (default), and the Local Roll Buffer has 1000 slots. The slot size used is identical with the roll file's slot size. The low water mark is 70 percent (default), the high water mark is 80 percent (default). 

//   EXEC PGM=NATRSMvr,PARM=',5,1000,150000,NATROLL1',MEMLIMIT=800M
//ROLLF1 DD DSN=DASD1.ROLLFILE
//ROLLF2 DD DSN=DASD2.ROLLFILE
//ROLLF3 DD DSN=DASD3.ROLLFILE
//ROLLF4 DD DSN=DASD4.ROLLFILE
//ROLLF5 DD DSN=DASD5.ROLLFILE

The subsystem ID is NATv (default), five roll files are used, and each of the five Local Roll Buffers has 1000 slots. The LRB slot size is 150000 bytes. The roll file directory resides in the Coupling Facility structure NATROLL1. Low and high water marks are 0 (which is the default for Sysplex) resulting in every thread being written to the roll file. The MEMLIMIT option specifies 800 MB for the Local Roll Buffers. 

//   EXEC PGM=NATRSMvr
//ROLLF1 DD DSN=SYSF.ROLLFILE
//RSMPARM DD DSN=FB.SYSF.PARMS(RSMPARM1)

File FB.SYSF.PARMS(RSMPARM1): 

Subsid=TST1
NumFiles=1
NumSlots=200
Lowwater=4
Highwater=6
*Structure=FBROLLS       Comment: No Sysplex today
NonActivity=2            Hours
TimeoutRepeat=240        Minutes

The subsystem ID is TST1, 1 roll file is used, the LRB has 200 slots. The low water mark is set to 40 percent, the high water mark to 60 percent. Every 4 hours a timeout check is run, killing all sessions that have been idle for at least 2 hours.

Anmerkung:
The Roll Server will not start in the following cases:

  • Another Roll Server is running with the same subsystem-id.

  • Another Roll Server is accessing a roll file specified in its JCL

  • A roll file has been reformatted without resetting the CF structure, using the SETXCF FORCE command.

Roll Server Messages, Condition Codes and Abend Codes

The Roll Server writes informational and error messages to JESMSGLG using the WTO macro (ROUTCDE=11). The messages are preceded by a message identifier and the Roll Server's job name, for example: 

RSM0019 FBRSMvrs: Roll Server Version vrs is active

where vrs represents the relevant Roll Server version.

The messages are explained in the section Roll Server Messages in the Messages and Codes documentation.

Condition Codes of the Roll Server Started Task

The following condition codes are used:

0 Normal completion
12 Parameter error
16 Runtime error
20 Abend has occurred
>100 Initialization error

User Abend Codes

When an unexpected return code is issued by an XCF or XES Service Call, an abend with a dump is forced. Register 14 of the abend register contains the reason code. To find a description of the reason, refer to Programming: Sysplex Services Reference (IBM documentation). If the error was not environment-specific, send the dump to Software AG support.

The following user abend codes are used:

Abend Code Cause
U0200 IXLCONN failed
U0201 IXLFORCE failed
U0202 IXLLIST failed
U0203 IXLDISC failed
U0204 IXCLEAVE failed
U0301 IXLLIST failed
U0302 IXCMSGO failed
U0401 IXLLIST failed
U0501 IXLLIST failed

Return Codes and Reason Codes of the Roll Server Request

These are codes that Natural may receive from the Roll Server's PC services routines. They are reported by the respective teleprocessing interfaces (Natural CICS Interface or Natural IMS TM Interface). For a list of these codes, refer to the Return Codes and Reason Codes of the Roll Server Request in the Messages and Codes documentation.

Operating the Roll Server

The following commands can be passed to the Roll Server via the MODIFY operator command:

Command Description
DIAGNOSE Debugging function, only to be used at Software AG's advice.

This command does not have any function. Its intended future use is in connection with special Zaps to aid in diagnosing specific customer problems, as the need arises.

HWM n Sets the LRB high water mark to n times 10 percent of the number of LRB slots (n=0-10). If n is not specified, the current low and high water marks are displayed.
LWM n Sets the LRB low water mark to n times 10 percent of the number of LRB slots (n=0-9). If n is not specified, the current low and high water marks are displayed.
SNAP Debugging function. The Roll Server's address space is dumped to SYSUDUMP.
STATS Write Roll Server statistics to JESMSGLG using the WTO macro (ROUTCDE=11). Statistics include information about roll-out and roll-in activity, as well as roll file I/O.
TERM Stops the Roll Server. The roll file directory and all modified LRB slots are written to the roll file and the address space is terminated. The address space ID is no longer available until the next IPL.

Statistics are written to JESMSGLG using the WTO macro (ROUTCDE=11). Statistics include information about roll-out and roll-in activity, as well as roll file I/O.

TIMEOUT NAT nnn Specifies or replaces the non-activity time parameter.
TOC hhmm Specifies or replaces the time of day of the timeout check.
OFF Disables timeout checking.
ON Reinstates timeout checking.
NOW Starts an immediate timeout check. Normal timeout check scheduling (if specified) remains in effect.
REPEAT nnnn Requests that the timeout check be run every nnnn minutes.
TERSE Suppresses the messages RSM0072 and RSM0074 during TIMEOUT NOW processing. Message RSM0047 Operator command: TIMEOUT NOW is also suppressed.
VERBOSE Displays the messages RSM0072, RSM0074 and RSM0047 Operator command: TIMEOUT NOW. This is the default setting.
?

(or no specification)

 Displays current timeout settings. The question mark (?) is optional and can be omitted.

Resetting the Coupling Facility Structure

When a TP Monitor or server region which uses the Roll Server abends, the Roll Server might return an error. For example, the Roll Server directory might be reported as full because session cleanup had not been performed before the region abended. To resolve such an error, delete the respective Coupling Facility structure:

  1. Shut down all Roll Servers which use the affected CF structure.

  2. Issue the operator command SETXCF FORCE,STR,STRNAME=structure-name, where structure-name is the name of the CF structure used for the Roll Servers.

  3. Restart all Roll Servers.

  4. Format the Roll Files.

If, under normal operation, the Roll Files or the LRB become full due to the number of concurrently active users, restart the Roll server and specify larger Roll Files or a larger LRB.

You can also monitor the usage of Roll Files with the SYSTP utility.

Roll Server Performance Tuning

As a general rule for Roll Server performance tuning, give the Roll Server a higher dispatching priority than the address spaces where Natural runs.

To find out where the weaknesses in performance are, analyze the system performance using the Natural Subsystems and Roll Server Information function of the SYSTP utility.

When looking at Roll-Server Statistics, keep an eye especially on the following values:

  • The number of direct writes.

    "Direct write" means that the Natural thread that was received was written to the roll file directly.

    There are two possible reasons:

    1. No LRB slot available. Increase the LRB.

    2. The compressed thread was larger than a single LRB slot. Increase the LRB slot size.

  • The number of direct reads.

    "Direct read" means that the requested thread was no longer in the LRB and had to be read directly from the roll file.

    If the ratio of direct reads to the total number of reads is very high in a single z/OS system, the LRB is too small (increase it).

    If the ratio of direct reads to the total number of reads is very high in a z/OS Parallel Sysplex environment, this may also mean that there are many inter-system activities, which in turn means that a Natural session changes z/OS images quite frequently during its lifetime.

  • The number of staging waits (in a single z/OS environment).

    A "staging wait" is a situation where a write request had to wait until the Staging Task had written the LRB slot to the roll file. If the ratio of staging waits to the total number of write requests is very high, this indicates that the high and low water marks are set inappropriately or that there is a bottleneck on the roll file device/roll file channel.

    Based on experience with stress tests, the following is recommended:

    If the ratio of maximal number of active users to number of LRB slots is very small, increase the high water mark. If not, decrease the high water mark.

    The difference between high water mark and low water mark should not be larger than three (30 percent).

    Ideally, if the number of LRB slots is definitely larger than the maximum number of concurrent users, the high water mark should be set to 10.

Roll Server User Exits

The roll server has two user exits.

Sample source modules are delivered for these.

NATRSU14 User Exit

Specifies the roll file number to be used.

Entry calling conventions:

  • Register 1 addresses the parameter list that is described by the following DSECT: 

    PLIST      DSECT
PLRSVER    DS CL4    Roll server version  (= '851')
PLNRF      DS H      Number of roll files
PLUID      DS CL16   Userid
PLTSNUM1   DS H      Total number of slots  Roll file 1
PLUSNUM1   DS H      Number of slots in use Roll file 1
PLTSNUM2   DS H      Total number of slots Roll file 2
PLUSNUM2   DS H      Number of slots in use Roll file 2
PLTSNUM3   DS H      Total number of slots Roll file 3
PLUSNUM3   DS H      Number of slots in use Roll file 3
PLTSNUM4   DS H      Total number of slots Roll file 4
PLUSNUM4   DS H      Number of slots in use Roll file 4
PLTSNUM5   DS H      Total number of slots Roll file 5
PLUSNUM5   DS H      Number of slots in use Roll file 5
PLISTL EQU *-PLIST

  • Register 13 points to a 36-fullword save area.

  • Register 14 contains the return address.

  • Register 15 contains the entry address of NATRSU14.

Return calling convention:

  • Register 15 contains the number of the roll file in binary format.

Anmerkung:
If access registers are modified within this user exit, these access registers must be saved and restored on return. This user exit is called in primary addressing mode with PSW Key 8. Since it runs in cross-memory mode, no SVC except SVC 13 may be used.

NATRSU24 User Exit

Specifies the XCF group name to be used.

Entry calling conventions:

  • Register 1 points to an 8-byte area in which the group name must be generated.

  • Register 13 points to an 18-fullword save area.

  • Register 14 contains the return address.

  • Register 15 contains the entry address of NATRSU24.

As a group name default, the Roll Server will use the leftmost 8 bytes of the CF structure name.

This user exit is called in primary mode, PSW Key 8 and in task mode.