Unlike automatic checkpoint-restart, deferred checkpoint-restart requires that certain JCL changes be made before resubmitting the job.
The requirements for a deferred restart are:
-
A SYSCHK DD statement must appear immediately before the first EXEC statement in the job. The SYSCHK DD must use the same DSN name as the SORTCKPT DD of the sort that failed. Specify UNIT, VOL=SER, and DISP=(OLD,KEEP).
-
The RESTART parameter must be specified, and must provide the job stepname and the PROC stepname (if any) associated with the step containing the failed sort, as the first subparameter. (Separate the two stepnames by a period.) The second subparameter should contain the checkpoint ID of the last checkpoint taken before the sort failed. This can be determined from the console messages given for the job. For JCL sorts, the ID is usually "Cnnnnnnn," referring to the sequence number assigned by the operating system.
-
SORTIN and SYSIN DD DUMMY statements are permissible if the program is being restarted at a point where they are no longer needed.
Figure 1. Sample Deferred Checkpoint-Restart JCL Stream
This JCL differs from automatic checkpoint-restart JCL.