When you specify PURGE with the DUMP parameter, PURGE specifies that DFSMShsm delete all volume information for a dump volume. DFSMShsm removes the record of the deleted volume from the BCDS. In addition, DFSMShsm deletes any association with the day in the dump cycle or with the dump class. DFSMShsm also deletes any valid dump copies. The dump volume then becomes a scratch tape.
Depending upon the tape security option used for protection by DFSMShsm, the volume may have to be reinitialized before being reused by another user or job.