Local request queue data set maintenance

You must regularly perform maintenance on the local request queue (LRQ) data set to prevent the data set from becoming too large.

The key of the LRQ data set includes a time stamp. This means that BTS generally adds requests to the end of the file. Although BTS deletes requests when they have completed, VSAM does not physically delete the records; so the space is not reused. Therefore, you must perform regular maintenance on the local request queue (LRQ) data set to prevent the data set from becoming too large.

You can use an AMS command such as REPRO to shrink the data set. For example, to remove the records that have been logically deleted by VSAM. Before using the REPRO command, you must quiesce CICS®. Disabling the LRQ file definition is not sufficient - if you only disable the LRQ file definition, activations might fail with ASP7 abends.

Before undertaking maintenance, quiesce the CICS region. If you use CICSPlex® SM for routing BTS activities, you could route work away from the region by altering a CICSPlex SM workload definition (WLMDEF). If you use a CICS distributed routing program, you could alter your routing program. Although the region has been temporarily quiesced, BTS operations in the sysplex are uninterrupted.

When reorganizing the data set, consider the percentage of control areas specified on the FREESPACE parameter on the cluster definition. If there are many records representing timers far in the future, and new timers are to be added for events that will expire earlier than these existing records, a large FREESPACE percentage will decrease the number of likely control area splits that might occur. If most new timer events are added for times later than existing events, the FREESPACE percentage for control areas can be set to 0.