Required parameters

ALTERNATEINDEX

Defines an alternate index or recatalogs an alternate index entry.

The ALTERNATEINDEX keyword is followed by the parameters for the alternate index as a whole. These parameters are enclosed in parentheses and, optionally, are followed by parameters given separately for the DATA and INDEX components.

Abbreviation: AIX

NAME(entryname)

Is the alternate index's entryname or the name of each of its components. The entry name specified for the alternate index as a whole is not propagated to the alternate index's components.

You can define a separate entry name for the alternate index, its data component, and its index component. If you do not give a name for the data or index component, one is generated. For more information about the system-generated name format, see z/OS DFSMS Managing Catalogs.

When the alternate index, data component, and index component are individually named, each can be addressed.

RELATE(entryname)

Names the alternate index base cluster. The base cluster is an entry-sequenced cluster or a key-sequenced cluster to which the alternate index is to be related. You cannot relate an alternate index to a reusable cluster, to a relative record cluster, to an extended addressability ESDS, or to a VVDS (data set name 'SYS1.VVDS.Vvolser'). An SMS-managed alternate index has the same management class and storage class as its base cluster.

Select the entryname so that the multilevel alias facility selects the same catalog as the one containing the related data set name.

Abbreviation: REL

CYLINDERS(primary[ secondary])|

KILOBYTES(primary[ secondary])|

MEGABYTES(primary[ secondary])|

RECORDS(primary[ secondary])|

TRACKS(primary[ secondary])

Is the amount of space in cylinders, kilobytes, megabytes, records, or tracks allocated to the alternate index from the volume's available space. A kilobyte and megabyte allocation resolves to either tracks or cylinders; records are allocated to the nearest track boundary.

Exception: If allocation resolves to tracks, the space is contiguous. For more information, see z/OS DFSMS Using Data Sets.

Requests for space are directed to DADSM and result in a format-1 DSCB for the data and index component entries.

If you do not use the MODEL parameter or the RECATALOG parameter, you must include one, and only one, of these parameters: CYLINDERS, KILOBYTES, MEGABYTES, RECORDS, or TRACKS.

The space parameter is optional if the cluster is SMS-managed, but if you do not use it, space can be modeled or defaulted by SMS. If it is not determined, the DEFINE is unsuccessful.

To maintain device independence, do not use the TRACKS or CYLINDERS parameters. If you do not use TRACKS or CYLINDERS for an SMS-managed alternate index, space is allocated on the volume selected by SMS.

When you do not divide the data component into key ranges, and more than one volume is given, the primary amount of space is allocated only on the first volume when the component is defined. When the component increases to extend to additional volumes, the first allocation on each overflow volume is the primary amount.

Secondary amounts can be allocated on all volumes available to contain parts of the alternate index, regardless of the key ranges when the alternate index is extended.

You can include the amount of space as a parameter of ALTERNATEINDEX, as a parameter of DATA, or as a parameter of both DATA and INDEX:

If the space is specified as a parameter of ALTERNATEINDEX, the amount specified is divided between the data and index components. The division algorithm is a function of control interval size, record size, device type, and other data set attributes.
If the division results in an allocation for the data component that is not an integral multiple of the required control area size, the data component's allocation is rounded up to the next higher control area multiple. This rounding can result in a larger total allocation for your alternate index than what you specified.
If the space is specified as a parameter of DATA, the entire amount given is allocated to the data component. An additional amount of space, depending on control interval size, record size, device type, and other data set attributes, is allocated to the index component.

To determine the exact amount of space allocated to each component, list the alternate index's catalog entry, using the LISTCAT command.

The primary and each secondary allocation must be able to be satisfied within five extents; otherwise, your DEFINE or data set extension is unsuccessful.

You can use these keywords for both SMS-managed and non-SMS-managed data sets.

primary: Allocates the initial amount of space to the alternate index.
secondary: Allocates the amount of space each time the alternate index extends, as a secondary extent. If the secondary space allocation is greater than 4.0 gigabytes, it is reduced to an amount as close to 4.0 GB as possible, without going over. This is not true for extended addressability data sets, which have no such space limitation. When you use secondary, space for the alternate index's data and index components can be expanded to a maximum of 123 extents.

Abbreviations: CYL, KB, MB, REC, and TRK

VOLUMES(volser[ volser...])

Specifies the volumes on which an alternate index's components are to have space. This parameter is not required if the cluster is modeled or if the cluster is SMS-managed. You can specify VOLUMES for SMS-managed data sets; however, the volumes specified might not be used and, in some cases, can result in an error.

For SMS-managed data sets, you can use up to 59 volumes. If the combined number of volumes for a cluster and its associated alternate indexes exceeds 59, unpredictable results can occur.

You can let SMS choose the volumes for SMS-managed data sets by coding an * for the volser with the VOLUMES parameter. If both user-specified and SMS-specified volumes are requested, the user-specified volser must be input first in the command syntax. The default is one volume.

If you do not use the MODEL parameter, VOLUMES must be placed as a parameter of ALTERNATEINDEX, or as a parameter of both DATA and INDEX.

If the data and index components are to reside on different device types, you must include VOLUMES as a parameter of both DATA and INDEX. If more than one volume is listed with a single VOLUMES parameter, the volumes must be the same device type.

You can repeat a volume serial number in the list only if you use the KEYRANGE parameter. This can place more than one key range on the same volume. However, repetition is valid only if all duplicate occurrences are used for the primary allocation of some key range.

The VOLUMES parameter interacts with other DEFINE ALTERNATEINDEX parameters. Ensure that the volumes you define for the alternate index are consistent with the alternate index's other attributes:

CYLINDERS, RECORDS, TRACKS: The volumes contain enough available space to satisfy the component's primary space requirement.
FILE: To define an alternate index, the volume information supplied with the DD statement pointed to by FILE must be consistent with the information listed for the alternate index and its components.

Abbreviation: VOL