Specifying Descriptive Information for an Alternate Index

You need to specify the following descriptive information for an alternate index:

The name and password of the base cluster related to the alternate index, as specified in the RELATE parameter. The RELATE entry name must be selected so that the multilevel alias facility selects the correct catalog. See z/OS DFSMS Managing Catalogs for information about the multilevel alias facility and z/OS DFSMS Access Method Services Commands for information about the order of catalog search.
Amount of space to allocate for the alternate index, as specified in the CYLINDERS|KILOBYTES|MEGABYTES|RECORDS|TRACKS parameter.
Volume serial numbers of the volumes on which space is allocated for the alternate index, as designated in the VOLUMES parameter. If you specify the VOLUMES parameter for system-managed data sets, however, the volumes designated might or might not be used, and sometimes can result in a failure. You can indicate nonspecific volumes for a system-managed data set by designating an asterisk (*) for each volume serial. SMS then determines the volume serial. The default is one volume. Note that if both specific and nonspecific volumes are designated, the specified volume serials must be named first.
The minimum amount of I/O buffer space that OPEN must provide when the program processes the alternate index's data, as designated in the BUFFERSPACE parameter.
Name and password of the catalog containing the alternate index's entries, as designated in the CATALOG parameter. This must be the same catalog that contains the base cluster's entries.
Data class, for alternate indexes, to take advantage of the attributes assigned by the storage administrator.
Length and position of the alternate key field in data records of the base cluster, as specified in the KEYS parameter.
Average and maximum lengths of alternate index records, as specified in the RECORDSIZE parameter.
Whether the alternate index is reusable, as specified in the REUSE parameter.
Whether the data set is extended format and whether it has extended addressability. These characteristics for the alternate index are the same as those for the cluster.

The performance options and the security and integrity information for the alternate index are the same as that for the cluster. See Using Access Method Services Parameters.