Requeue from a SNAPQ checkpoint

Although simple checkpoints can be used in conjunction with an interval subcommand, BMC Software recommends by using a SNAPQ checkpoint if a DUMPQ checkpoint cannot be used or is not available.

To use a SNAPQ checkpoint, you must specify REQUEUE TYPE=EREFAIL even if the previous IMS system did not have an emergency restart failure. The checkpoint can be entered at the WTOR prompt, but it is a good practice to specify the checkpoint by using the CHKPT keyword in the command set.

The processing that the TYPE=EREFAIL option generates is similar to TYPE=REPROCESS processing. The only difference is that with TYPE=EREFAIL, messages dequeued during the course of a SNAPQ or messages dequeued between the x'4099' and the end of file (EOF) will cancel the messages that were on the queue at the beginning of the checkpoint or enqueued thereafter. Therefore, only messages that remain on the queues when EOF is reached are available for requeue to IMS or to an Extract file.

The following figure shows a command set for requeueing IMS transaction messages by using a SNAPQ checkpoint and an IMS Log. This command set overrides the SLDS (INPUT DSNAME=IMS.ARCHIVE.LOG), specifies a checkpoint (CHKPT=2001180/1234567), and creates an extract file (MODE=EXTRACT_REQUEUE).