Releasing a backup volume

When a backup volume task finishes using a backup volume, it releases the backup volume by deallocating it. If the backup volume being released is not full and another volume backup task in the same host is waiting for the type of backup volume being released, the other volume backup task is notified that the backup volume is available. DFSMShsm determines the amount of unallocated space remaining on the volume if the backup volume is a DASD volume. If the released backup volume is a virtual volume and you have specified the UNLOAD parameter of the SETSYS command, DFSMShsm issues the MVS™ UNLOAD command to unload this volume.