Do not recommend using DFHSMShsm to backup Librarian Master files.
If the first block of the Master file gets modified by DFSMShsm, it will corrupt the Master and make it unusable. Have seen Archived / Migrated Master files get corrupted when the Master file is restored.
If DFSMShsm is intended to do Migrations and Archiving, needs to have a Librarian backup that can be used to restore the Master file in case the Master file gets corrupted during the recall.