SYSLOCKS recommendation

Document ID : KB000009763
Last Modified Date : 14/02/2018
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Introduction:

Is there a recommended value for SYSLOCKS and is there any negative impact of increasing it?

Background:

Locking overflow indicated by DC015007 messages on pool 255.

Environment:
CA IDMS all supported releases
Instructions:

The recommended value for SYSLOCKS is 100,000 at the very least.

Some sites have been known to have it set as high as 1,000,000 or even more.

SYSLOCKS is not a number of locks of a certain size. It is a numerical seed used in a calculation which also involves other aspects of the sysgen which might indicate the size of the CV (e.g. MAXTASKS, number of LTERMs etc). These values are used to calculate an amount of storage allocated at startup to be used for locking.

This storage is above the line, operating system storage – i.e., it is not taken from the CV’s storage pools defined in the CV.

If this storage is exhausted, then overflow locking storage is taken from pool 255 – the CV’s system XA storage pool.

The amount of storage allocated at startup can be seen in the following message on the CV joblog:-

IDMS DC040102 V65 LOCK MANAGER STORAGE FORMATTED; 4476K USED

 

The only downside of increasing SYSLOCKS is that this amount of storage allocated will be larger.

Additional Information:

For more information, see the CA IDMS DocOps page on Database Locks.