VERSIONS and SYSVERSIONS: Specifying the number of backup versions to maintain

Explanation: VERSIONS and SYSVERSIONS are mutually exclusive, optional parameters specifying the maximum number of backup versions to be kept when additional versions are made for the data set.

VERSIONS(limit) is specified to change the number of backup versions to be kept for the specified data set. The maximum number of backup versions is limited to 29 versions or 100 versions based on the BCDS record length. The following values are the valid maximum allowable number of backup versions for different BCDS record lengths:

Record length of 2040 to 6543 — 29 versions maximum
Record length of 6544 or more — 100 versions maximum

For limit, substitute a decimal number from 0 to 100. If you specify 0, DFSMShsm does not back up the data set.

SYSVERSIONS is specified to revert to the value you specified with the SETSYS command or to the DFSMShsm default for the number of backup versions to be kept for backup data sets.

Defaults: None.

Note:

Specify the SYSVERSIONS parameter only if a previous ALTERDS command has changed the number of backup versions for this data set and if you want to return to the number of backup versions specified on the SYSVERSIONS setting. DFSMShsm determines the number of backup versions in the following order:
- ALTERDS
- SETSYS
- DFSMShsm default
If you reduce the number of backup versions with this command, DFSMShsm does not delete existing backup versions when the ALTERDS command is processed.
The existing excess backup versions will be deleted to match the specified limit at the time a new backup version is created for the data set. The EXPIREBV command can be used to delete unwanted backup versions of data sets without creating any new backup versions.
DFSMShsm can keep a maximum of 29 versions or 100 versions, depending on the BCDS record length. Some versions may be kept for a cataloged data set with that name, and some versions kept for uncataloged data sets with that name.
The VERSIONS or SYSVERSIONS parameter indicates the number of backup versions kept for (1) the cataloged data set and (2) the uncataloged data sets. DFSMShsm gives priority, if necessary, to versions of the cataloged data set. For example, if you specify VERSIONS(15), when the 15th backup version of the cataloged data set is made, no more than 14 versions will be kept for the uncataloged data sets.