Start of change

Migrating the DFHLRQ data set

The local request queue data set is used to store pending BTS requests, such as timer requests, or requests to run activities. It is recoverable, and is used to ensure that, if CICS fails, no pending requests are lost.

Requests that CICS can execute immediately, such as requests to run activities, are stored on the data set only briefly. Requests that CICS cannot execute immediately, such as timer or unserviceable requests, might be stored for longer periods. When CICS has processed a request, the request is deleted from the data set.

If you have outstanding BTS activities for BTS processes within CICS, you should migrate the contents of your DFHLRQ data set as part of the migration. A utility such as IDCAMS COPY could be used to update the CICS TS 3.1 DFHLRQ data set with the contents of the DFHLRQ data set from your previous CICS release.

Be aware that even if you are not explicitly making use of BTS services in your applications, it is possible that they are being exploited by vendor code or IBM-supplied products executing within your CICS environment.

PTFs for earlier CICS releases modified the dynamic routing DSECT used for dynamic DPL and dynamic start requests. This caused the structure of DFHLRQ records to change. The PTF numbers are:

CICS TS 1.3
PTF UQ82768 (APAR PQ75814)
CICS TS 2.2
PTF UQ82632 (APAR PQ75834)
CICS TS 2.3
PTF UQ85555 (APAR PQ81378)

If you have one of these PTFs applied to your existing CICS system, the DFHLRQ records match the format of DFHLRQ records used in CICS TS 3.1, and so can be migrated using a utility such as IDCAMS COPY. However, if you do not have one of these PTFs applied to your existing CICS system, the DFHLRQ record format is not compatible with that used in CICS TS 3.1. In this case, you should complete your BTS workload prior to migration to CICS TS 3.1, and start with an empty DFHLRQ at that release.

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