Consider using a large format data set for the DFSMShsm journal. A large format data set is a physical data sequential data set with the ability to grow beyond 65␠535 tracks per volume. Using a larger journal data set can allow more DFSMShsm activity to take place between journal backups and helps to avoid journal full conditions. For more information about large format data sets, see z/OS DFSMS Using Data Sets.

If you decide to migrate your current journal to a large format data set, use the following procedure:

1. Stop all but one of the DFSMShsm hosts.
2. Either enter the HOLD ALL command, or set DFSMShsm to emergency mode.
3. Back up the control data sets through the BACKVOL CDS command. Doing so creates a backup of the journal and nulls the journal.
4. Stop the remaining hosts.
5. Rename the current journal data set. Do not delete the data set yet because the new journal should not be allocated in place of the existing journal.
6. Allocate the new large format sequential journal data set. If you allocate the new journal data set with a name other than the old journal data set name, edit the DFSMShsm startup procedure to use the new journal data set name.
7. Restart the DFSMShsm hosts.

Because of the size of the journal, it might be impractical to perform Steps 5 and 6. As an alternative to these steps, you can delete the existing journal, allocate the new journal, and then run an IEBGENER or IDCAMS (using the REPRO command) job to copy zero records into the journal.