Problem: storage shortage in the lock structure

In a data sharing environment, you might encounter a problem that is caused by a storage shortage in the lock structure.

Symptom

A DXR170I message indicates when storage reaches 50, 60, and 70% full. However, because this problem is detected along with other timer driven function, some messages with lower percentages might be missing or skipped if the coupling facility is filling up rapidly. The following message appears at increasing thresholds starting at 80% full: 
-DB1A DXR142I irlmx THE LOCK STRUCTURE structure-name
      IS zzz%  IN USE

System action

Db2 continues processing, but some transactions might obtain a resource unavailable code because they are unable to obtain locks.

System programmer action

First, make sure that no members are down and holding retained locks. Restarting any failed members can remove the locks retained in the coupling facility lock structure and release that space.

If a failed member is not the problem, you have two courses of action:

  • Lower the lock escalation values to get fewer locks. You do this by taking one of the following actions:
    • Lowering the value of the LOCKS PER TABLE(SPACE) field of installation panel DSNTIPJ (NUMLKTS subsystem parameter)
    • Start of changeFL 507 Specifying or lowering the value of the SYSIBMADM.MAX_LOCKS_PER_TABLESPACE built-in global variable if the global variable is in use on the Db2 subsystemEnd of change
    • Specifying or changing the value of the LOCAKMAX clause of CREATE or ALTER TABLESPACE
  • Increase the size of the lock structure.