DFS1234I REQUESTED BLOCK DOES NOT EXIST IN $$IMSDIR.

Explanation
A delete request for a FMT/MSG descriptor has been unsuccessful. The requested
descriptors are not in $$IMSDIR.

System action
If delete, processing continues with next statement. If scratch, continue
with scratch processing.

Programmer response
If delete, specify the correct descriptor name. Resubmit the job.