Parameters

MODE=STAR

Directs the system to convert a global resource serialization ring complex to a global resource serialization star complex.

MODE=STAR is mutually exclusive with the RESMIL and TOLINT parameters.

RESMIL=nnnnnnnn | RESMIL=OFF

Specifies the RSA-message residency time. The value indicates the minimum RSA-message residency time in milliseconds (that is, the least amount of time that the RSA-message is to spend in this system). The actual amount of time that the RSA-message is to spend in this system will vary between the time you specify in milliseconds and a maximum value calculated by global resource serialization. In this way, global resource serialization balances CPU use and ENQ response time.

If you specify RESMIL=OFF, the RSA-message residency time is set to zero and global resource serialization does no tuning. If you specify RESMIL=0, the system tunes the residency time in a range with a minimum of zero.

The RESMIL value can be from 0 to 99999999 milliseconds, or OFF. If you omit the RESMIL parameter, the current RESMIL value remains in effect. The current value was specified either by the GRSCNFxx parmlib member or by a previous SETGRS command.

TOLINT=nnnnn

Specifies, in seconds, the maximum tolerance time interval global resource serialization allows the RSA-message to return to this system, before it considers the RSA-message overdue.

The value of TOLINT can be from 1 to 86399 seconds. If you omit the TOLINT parameter, the current TOLINT value remains in effect. The current value was specified either by the GRSCNFxx parmlib member or by a previous SETGRS command.

SYNCHRES=YES | NO

Specifies whether synchronous reserve processing is activated. Action is only taken on the system where the command is issued.

ENQMAXA | ENQMAXU=nnnnnnnn [,NOPROMPT]

Assigns a new global resource serialization system enqueue maximum value for concurrent authorized (ENQMAXA) or unauthorized (ENQMAXU) requesters in a single system. This function enables you to dynamically update workload estimation for enqueue processing. Global resource serialization attempts to update the appropriate enqueue maximum as specified. The ISGADMIN service can update the maximum values for a specific address space. Global resource serialization uses the greater of the two maximums for its checking. For more information, see z/OS MVS Programming: Authorized Assembler Services Reference EDT-IXG.

value

A required parameter specifies the new concurrent maximum ENQ request value.

The ENQMAXA range is 250,000 to 99,999,999. The default is 250,000.

The ENQMAXU range is 16,384 to 99,999,999. The default is 16,384.

See z/OS MVS Planning: Global Resource Serialization for complete guidance information.

NOPROMPT

An optional parameter that informs the system not to issue the confirmation message.

Abbreviation: NP

CNS=system-name [,NOPROMPT]

CNS assigns a new global resource serialization contention notifying system (CNS) in a star complex.

Restriction: CNS is only applicable in a star complex.

NOPROMPT: An optional parameter that informs the system not to issue the confirmation message.
Abbreviation: NP

GRSQ={LOCAL | CONTENTION | ALL}

This parameter is specific to star mode and affects how quickly a dump is taken. GRSQ is system-specific; action is only taken on the system where the command is issued.

Restriction: GRSQ is only applicable in a star complex.

AUTHQLVL=1

An optional parameter that allows you to change the active GRS AUTHQLVL value to 1. IBM suggests setting the AUTHQLVL to the maximum value of 2 through the GRSCNFxx parmlib member. It can be changed to 1 if it is determined that various products still require particular qnames to be unauthorized.

For information about authorized qnames, see z/OS MVS Planning: Global Resource Serialization.

The GRSCNFxx parmlib member allows you to use the default or reset the value for the global resource serialization ring or start complex. See the GRSCNFxx member in z/OS MVS Initialization and Tuning Reference.

To issue the command you must have appropriate access to the RACF resource name MVS.SETGRS.AUTHQLVL. See z/OS MVS Planning: Operations for more information.

Use the DISPLAY GRS command to return information about the level for authorized qnames that are in effect.

MONITOR={YES|NO}

This parameter indicates whether to write SMF 87 monitoring records. MONITOR is system-specific; the parameter only affects the system on which the command is issued. To issue the command, you must have access to the RACF resource MVS.SETGRS.MONITOR.

GRSMON=XX

This parameter indicates the GRSMONxx parmlib member to use to determine which requests to monitor when MONITOR=YES.

Notes:

GRSMON is system-specific; the parameter affects only the system on which the command is issued.
To issue the command, you must have access to the RACF resource MVS.SETGRS.GRSMON.
You may specify only a single GRSMONxx parmlib member on SETGRS. Specifying a concatenation of multiple GRSMONxx members is not supported.

For more information about GRSMONxx, see z/OS MVS Initialization and Tuning Reference. End of change

Note:

The system on which you enter the SETGRS MODE=STAR command controls the migration.
When global resource serialization completes the transition to the star complex, the system issues the following message to indicate that the migration has completed and global resource serialization is active for the complex:
```
ISG334I GRS STAR COMPLEX INITIALIZATION COMPLETE
```
During processing of a SETGRS MODE=STAR command, no global resource requests (ENQ, DEQ, or RESERVE) will be processed. The length of time global resource serialization requesters are suspended may be several minutes, because the global resource serialization lock structure and sysplex couple data set records are going to be initialized with all of the complex-wide information, along with significant changes to the internal control block structures. IBM® recommends invoking the migration capability at a time of minimal global resource serialization activity.
A SETGRS MODE=STAR request is valid if the following criteria are met:
- Global resource serialization is running a ring complex.
- All systems in the global resource serialization ring complex support a star complex.
- There are no systems in the global resource serialization ring complex that are interconnected through the global resource serialization channel-to-channel support rather than the coupling facility.
- All systems can access the ISGLOCK lock structure on the coupling facility.
- The global resource serialization records are defined on the sysplex couple data set.
- There are no dynamic RNL changes still in progress.
The RESMIL and TOLINT parameters are not valid on a SETGRS command issued in a global resource serialization star complex.
The RESMIL and TOLINT parameters of the SETGRS command affect only the system on which the SETGRS command is issued.
A SETGRS CNS=sysname request is only valid if the following criteria are met:
- Global resource serialization is running in star complex.
- All systems in the global resource serialization star complex support SETGRS CNS command (systems are at or above z/OS® V1R7 with the required PTF).
- The target system is an active system in the global resource serialization star complex.