Using the XICERES exit to check the availability of resources on the target region

You can use an XICERES global user exit program to check that all resources required by the started transaction are available on the target region.

The XICERES exit is invoked, if enabled, on the target region before CICS® processes a dynamically-routed START request.

If, for example, the transaction to be started is disabled on the target region, or a required file is missing, your exit program can give the distributed routing program the opportunity to route the request to a different region. To do this, it should set a return code of UERCRESU. This causes CICS to:
  1. Return a RESUNAVAIL condition on the EXEC CICS START command executed by the mirror on the target region. (This condition is not returned to the application program.)
  2. Set the DYRERROR field of the routing program's communications area to 'F'—resource unavailable.
  3. Reinvoke the routing program, on the routing region, for route selection failure—see If an error occurs in route selection.

For information about writing an XICERES global user exit program, see Interval control EXEC interface program exits (XICEREQ, XICERES, and XICEREQC).

If a required resource is unavailable on the target region, but the XICERES exit is unavailable or disabled (or is enabled but does not set the UERCRESU return code), the client program receives an error response.