You can gain addressed or control interval access to the index component of a key-sequenced cluster by opening the index component alone and using the request macros for normal data processing. To open the index component alone, specify: DSNAME=indexcomponentname in the DD statement identified in the ACB (or GENCB) macro.
You can gain access to index records with addressed access and to index control intervals with control interval access. The use of these two types of access for processing an index is identical in every respect with their use for processing a data component.
Processing the index component alone is identical to processing an entry-sequenced data set. An index itself has no index and thus cannot be processed by keyed access.