If the storage class indicates tape media and the Tape storage group that specifies the tape volume allocation is for a tape library dataserver, the allocation process uses the DATACLASS parameter on the SETOAM statement to determine tape compaction or no tape compaction for the volume. If the TAPECOMPACTION or NOTAPECOMPACTION keywords on the SETOAM statement are specified for a particular storage group, the data is written in compacted or noncompacted format as specified. If these keywords are not specified at storage group level of the SETOAM statement, the DATACLASS parameter of the SETOAM statement at the global level is used to determine tape compaction or no tape compaction. Should the DATACLASS parameter not be specified at the OAM global level, information that is passed on the DEVSUP parameter after allocation processing is used to determine whether the allocated tape volume should have tape compaction or no tape compaction.

See Media selection for object storage for more information.