RELEASE command for DFSMSdss

The RELEASE command releases allocated but unused space from all eligible sequential, partitioned, and extended-format VSAM data sets that pass INCLUDE, EXCLUDE, and BY filtering criteria. The RELEASE command does not release space from guaranteed-space VSAM extended-format data sets. DFSMSdss only selects data sets that have space that can be released.

DFSMSdss offers two ways to process RELEASE commands:

Logical processing operates on a single selected data set at a time. The data set can be multivolume. The user has the option to not specify volumes or to specify one or more volumes with the LOGDDNAME, LOGDYNAM, or STORGRP keywords. Releasing unused space from extended-format VSAM data sets requires logical processing.
If no input volumes are specified and the INCAT keyword is not specified, DFSMSdss selects from all data sets cataloged in the catalogs accessible through the standard search order. For INCAT keyword details, see the INCAT keyword description in this section.
Physical processing operates on all selected data sets that reside on a single volume. The user must specify one or more volumes with the DDNAME or DYNAM keywords. You cannot use physical processing to release unused space from extended-format VSAM data sets.

To process multivolume data sets, do one of the following:

Specify no input volumes.
Specify LOGDDNAME, LOGDYNAM, or STORGRP with an appropriate SELECTMULTI option or a volume list.
Specify DDNAME or DYNAM with the volume or volumes on which the data set has space that can be released.

You must exclude, by using the EXCLUDE keyword, data sets whose last used block pointer in the data set’s VTOC entry are not properly maintained. This can occur if you use an access method other than BSAM, QSAM, or BPAM. DFSMSdss does not release any space for data sets that are empty (the last used block pointer in the data set’s VTOC entry is zero). This restriction does not apply to PDSE data sets; used space in PDSE data sets is maintained internally, rather than by reference to the data set’s VTOC entry.

The following apply to the RELEASE command:

A data set with the maximum number of extents already in use will not have any space released. For an extended-format VSAM data set, the maximum is 255 extents. For a partitioned data set extended (PDSE) and an extended-format sequential data set, the maximum is 123 extents. For other partitioned and sequential data sets, the maximum is 16 extents.
For extended-format VSAM data sets, DFSMSdss releases space from only the data component of a base cluster or an alternate index (AIX®).
For striped VSAM data sets, DFSMSdss releases eligible space from each stripe.
Free tracks in cylinder-allocated extents are not released. Only free cylinders are released.
DFSMSdss excludes system data sets beginning with SYS1, unless the PROCESS keyword is used.
DFSMSdss logical processing releases space from each volume on which an extended-format sequential data set contains data.
DFSMSdss does not support the release of HFS data sets, as the DADSM PARTREL macro no longer supports HFS data sets.
DFSMSdss does not support the release of zFS data sets.

For additional information about filtering, see DFSMSdss filtering—choosing the data sets you want processed.