The data set name (DSNAME) parameter specifies the name of the data set being processed. For a new data set, the specified name is assigned to the data set. For an existing data set, the system uses the name to locate the data set.
Optionally, the DSNAME parameter can be used to specify one of the components of a VSAM data set. Each VSAM data set is defined as a cluster of one or more components. Key-sequenced data sets contain a data component and an index component. Entry-sequenced and linear data sets and fixed-length RRDSs contain only a data component. Process a variable-length RRDS as a cluster. Each alternate index contains a data component and an index component. For further information on specifying a cluster name see Naming a Cluster.