RECOVER function description

Use the RECOVER function to select cold shared queue records for reprocessing, for deletion, and for possible reinsertion.

In a shared-queues environment, cold starts do not erase messages from the shared queues. Also, it is impossible in the shared queue environment for a single IMS to keep track of the status of a message that is inserted into the shared queues, because another IMS can remove and process that message.

For these just stated reasons, IMS does not log messages to the IMS log during checkpoint processing. DUMPQ and SNAPQ checkpoints are not done, and IMS Queue Control Facility cannot perform RECOVERAB or RECOVERDM processing.

However, IMS Queue Control Facility can recover messages on the cold shared queue that were in process when IMS abended and was then cold started. You can perform this recovery with the RECOVER function.

The RECOVER function keyword invokes the IMS Queue Control Facility recover logic that selects records from the cold shared queue for reprocessing, for deletion, for possible later insertion by the load function logic, or for purely informational purposes. IMS Queue Control Facility recover logic performs the following tasks:

  1. Processes control blocks that were built by IMS Queue Control Facility from input control statements:
    • Determines record selection criteria from the date and timestamps, and the record type from the SELECT statement
    • Determines record selection criteria from message sources, and destinations from the INCLUDE and EXCLUDE statements
  2. Writes to the RECOVER data set records that do meet the selection criteria of the SELECT, INCLUDE, and EXCLUDE statements
  3. Requeues and unlocks, or deletes messages that meet the selection criteria of the SELECT, INCLUDE, and EXCLUDE statements
  4. Discards records that fail to meet the selection criteria of the SELECT, INCLUDE, and EXCLUDE statements
  5. Produces reports on the number and types of messages that the RECOVER function recovered from the cold shared queue
  6. Returns control to IMS Queue Control Facility control processing

The job steps that are required for the RECOVER function are as follow: RECOVER