VLS: Volumes Group

The fields in this group identify the volume on which a data component, index component, user catalog, or non-VSAM data set is stored. It also identifies candidate volumes for a data or index component. The fields describe the type of volume and give, for a data or index component, information about the space the object uses on the volume.

If an entry-sequenced or relative record cluster's data component has more than one VOLUMES group, each group describes the extents that contain data records for the cluster on a specific volume.
If a key-sequenced cluster's data component has more than one VOLUMES group, each group describes the extents that contain data records for the cluster, or one of its key ranges, on a specific volume.
If a key-sequenced cluster's index component has more than one VOLUMES group, each group describes the extents that contain index records for the cluster, or one of its key ranges, on a specific volume. The first VOLUMES group describes the extent that contains the high-level index records (that is, index records in levels above the sequence set level). Each of the next groups describes the extents that contain sequence-set index records for the cluster, or one of its key ranges, on a specific volume. The index component of a key-sequenced data set with the IMBED attribute will have a minimum of two volume groups, one for the embedded sequence set, and one for the high-level index. The extents for the embedded sequence set are the same as those for the data component.

BYTES/TRACK—The number of bytes that VSAM can write on a track (listed for page spaces only).

DEVTYPE—The type of device to which the volume belongs.

EXTENT-NUMBER—The number of extents allocated for the data or index component on the volume.

EXTENT-TYPE—The type of extents:

00—The extents are contiguous.
40—The extents are not preformatted.
80—A sequence set occupies a track adjacent to a control area.
FF—A candidate volume.

EXTENTS—Gives the physical and relative byte addresses of each extent.

LOW-CCHH—The track address of the beginning of the extent where CCHH is a 28-bit cylinder address. A 28-bit cylinder address is described by the X'CCCCcccH' format, where 'ccc' is the high order 12-bits and 'CCCC' is the low order 16-bits of the cylinder address. The 'H' is the 4-bit track address. The high order 12-bits 'ccc' will be non-zero for a cylinder address greater than 65535.
LOW-RBA—The RBA (relative byte address), in decimal, of the beginning of the extent.
TRACKS—The number of tracks in the extent, from low to high device addresses.
HIGH-CCHH—The track address of the end of the extent where CCHH is a 28-bit cylinder address. A 28-bit cylinder address is described by the X'CCCCcccH' format, where 'ccc' is the high order 12-bits and 'CCCC' is the low order 16-bits of the cylinder address. The 'H' is the 4-bit track address. The high order 12-bits ('ccc') will be non-zero for a cylinder address greater than 65535.
HIGH-RBA—The RBA (relative byte address), in decimal, of the end of the extent.

HIGH-KEY ¹ —For a key-sequenced data set with the KEYRANGE attribute, the highest hexadecimal value allowed on the volume in the key field of a record in the key range. A maximum of 64 bytes can appear in HIGH-KEY.

HI-KEY-RBA ¹—For a key-sequenced data set, the RBA (relative byte address), in decimal, of the control interval on the volume that contains the highest keyed record in the data set or key range.

LOW-KEY ¹—For a key-sequenced data set with the KEYRANGE attribute, the lowest hexadecimal value allowed on the volume in the key field of a record in the key range. A maximum of 64 bytes can appear in LOW-KEY.

PHYRECS/TRK—The number of physical records (of the size indicated under PHYRECS-SIZE) that VSAM can write on a track on the volume.

PHYREC-SIZE—The number of bytes that VSAM uses for a physical record in the data or index component.

HI-A-RBA—The highest RBA (plus 1) available within allocated space to store data component, its key range, the index component, or the sequence set records of a key range.

HI-U-RBA—The highest RBA (plus 1) within allocated space that actually contains data component, its key range, the index component, or the sequence set records of a key range. (The RBA of the next completely unused control interval.)

TRACKS/CA—The number of tracks in a control area for the component being listed. (This value is computed when the entry is defined. This value reflects the optimum size of the control area for the given device and the nature of the entry, whether indexed, nonindexed, or numbered.) For a key-sequenced data set with the imbedded attribute, this value includes the sequence set track.

VOLFLAG—Indicates if the volume is a candidate volume and if the volume is a prime or overflow volume on which data in a given key range is stored.

CANDIDATE—The volume is a candidate for storing the data or index component.
CAND-SPACE—The volume is a candidate for storing the data or index component, and it has a primary extent preallocated (the data set was defined with a guaranteed-space storage class).
OVERFLOW—The volume is an overflow volume on which data records in a key range are stored. The KEYRANGE begins on another (PRIME) volume.
PRIME—The volume is the first volume on which data records in a key range are stored.

VOLSER—The serial number of the volume.