DUMPCLASS(STACK): Specifying the maximum number of dump copies that are stacked for this dump class

Explanation

STACK is an optional parameter of the DEFINE DUMPCLASS command. The STACK parameter specifies how many dump copies DFSMShsm should place on a dump volume (assigned to the specified dump class) during one invocation of automatic dump or BACKVOL dump.

The following is a required parameter of the STACK parameter:
nnn
The number (between 1 and 255) of dump copies that are stacked on a dump volume.

All stacking to a given tape is done while that tape is mounted. DFSMShsm selects empty dump volumes as targets for auto or command dump. Each dump copy is written in its own file, with a unique data set name. As dump generations are rolled off when new dumps are created, a dump volume may contain a combination of valid and not valid dump copies.

A given dump volume:
  • Regardless of the STACK value that is used to write to it, is associated with only one dump class.
  • Never contains more than one dump copy of the same source volume.
  • Can contain dump copies of both SMS-managed volumes and non-SMS-managed volumes.
  • Contains dump copies of only source volumes with affinity to the autodump host, or source volumes without such affinity, not a combination of both. System affinity can only be specified for SMS-managed volumes.

Defaults

If you do not specify STACK for a new dump class, DFSMShsm uses the value of 1. If you do not specify STACK for a dump class that is already defined, the previous STACK value remains unchanged.

Usage notes:
  1. If you specify a stack value greater than 99, verify the BCDS maximum record size is 6544 bytes. If it is not, redefine the BCDS with a maximum record size of 6544 bytes. For more information about redefining the BCDS and maximum record size requirements, see z/OS DFSMShsm Implementation and Customization Guide.
  2. DFSMShsm ignores any STACK value from DEFINE during a BACKVOL DUMP command for a list of volumes, unless you specify the dump class with the DUMPCLASS parameter on the BACKVOL command.
  3. VTOCCOPIES are created or not created in the same manner for all volumes dumped to the same dump class.
  4. Any RETENTIONPERIOD or EXPIRATIONDATE for the dump class applies to all the dump copies that are written to its dump volumes (all dump copies stacked on a dump volume expire on the same day).
Parent topic: Optional parameters of the DEFINE command