z/OS V1R6.0 DFSMS Access Method Services for Catalogs

DEFINE CLUSTERSpace is allocated for a linear data set with the number of control intervalsequal to the number of records. Linear data sets cannot be accessed forRLS processing. The LOG, LOGSTREAMID, and BWO parameters do notapply to linear data sets.Restriction: Linear data sets cannot be accessed for VSAM RLS orDFSMStvs processing. The LOG, LOGSTREAMID, and BWO parametersdo not apply to linear data sets.Abbreviation: LINNONINDEXEDIndicates that the cluster being defined is for entry-sequenced data. Thedata records can be accessed sequentially or by relative-byte address(RBA).Abbreviation: NIXDNUMBEREDSpecifies that the cluster’s data organization is for relative record data. Arelative record cluster, which is similar to an entry-sequenced cluster, hasfixed-length records or variable-length records that are stored in slots. TheRECORDSIZE parameter determines if the records are fixed-length orvariable-length. Empty slots hold space for records to be added later. Thedata records are accessed by relative record number (slot number).Abbreviation: NUMDKEYS(length offset|64 0)Provides information about the prime key field of a key-sequence data set’sdata records.This parameter overrides any KEYS specification on the DATACLASSparameter.This parameter applies only to key-sequenced clusters. The default is a keyfield of 64 bytes, beginning at the first byte (byte 0) of each data record.The key field of the cluster’s index is called the prime key to distinguish itfrom other keys, called alternate keys. See Chapter 13, “DEFINEALTERNATEINDEX,” on page 127 for more details on how to choose alternateindexes for a cluster.When the data record spans control intervals, the record’s key field must bewithin the part of the record that is in the first control interval.length offsetspecifies the length of the key and its displacement (in bytes) from thebeginning of the record. The sum of length plus offset cannot exceed thelength of the shortest record. The length of the key can be 1 to 255 bytes.LOG(NONE|UNDO|ALL)Establishes whether the sphere to be accessed with VSAM record-level sharing(RLS) or DFSMStvs is recoverable or non-recoverable. It also indicates whetheror not forward recovery logging should be performed for the data set. LOGapplies to all components in the VSAM sphere. VSAM uses LOG in thefollowing way:Nonrecoverable SphereThe sphere is considered nonrecoverable if LOG(NONE) is specified.VSAM allows concurrent read and update sharing across multiple resourcemanagers and other applications.Chapter 14. DEFINE CLUSTER 157