Stopping the IRLM

If the internal resource lock manager (IRLM) is started automatically by Db2, it stops automatically when Db2 is stopped. If the IRLM is not started automatically, you must stop it after Db2 stops.

Procedure

To stop IRLM:

Issue the z/OS STOP irlmproc command.

If you try to stop the IRLM while Db2 or IMS is still using it, you get the following message:

Begin general-use programming interface information.

DXR105E irlmnm STOP COMMAND REJECTED. AN IDENTIFIED SUBSYSTEM
IS STILL ACTIVE

If that happens, issue the STOP irlmproc command again, when the subsystems are finished with the IRLM.

Alternatively, if you must stop the IRLM immediately, enter the following command to force the stop: 

MODIFY irlmproc,ABEND,NODUMP
The system responds with this message: 
DXR165I KRLM TERMINATED VIA IRLM MODIFY COMMAND.
DXR121I KRLM END-OF-TASK CLEANUP SUCCESSFUL - HI-CSA 335K
-  HI-ACCT-CSA      0K  -  HI-PVT   5402K

Results

Your Db2 subsystem will abend. An IMS subsystem that uses the IRLM does not abend and can be reconnected.

IRLM uses the z/OS Automatic Restart Manager (ARM) services. However, it de-registers from ARM for normal shutdowns. IRLM registers with ARM during initialization and provides ARM with an event exit routine. The event exit routine must be in the link list. It is part of the IRLM DXRRL183 load module. The event exit routine ensures that the IRLM name is defined to z/OS when ARM restarts IRLM on a target z/OS system that is different from the failing z/OS system. The IRLM element name that is used for the ARM registration depends on the IRLM mode. For local-mode IRLM, the element name is a concatenation of the IRLM subsystem name and the IRLM ID. For global mode IRLM, the element name is a concatenation of the IRLM data sharing group name, IRLM subsystem name, and the IRLM ID.

IRLM de-registers from ARM when one of the following events occurs:

  • PURGE irlmproc is issued.
  • MODIFY irlmproc,ABEND,NODUMP is issued.
  • Db2 automatically stops IRLM.

The command MODIFY irlmproc,ABEND,NODUMP specifies that IRLM de-register from ARM before terminating, which prevents ARM from restarting IRLM. However, this command does not prevent ARM from restarting Db2, and, if you set the automatic restart manager to restart IRLM, Db2 automatically starts IRLM.End general-use programming interface information.