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

DEFINE CLUSTERIf REUSE or NOREUSE is specified in the SMS data class, the value defined isused as the data set definition, unless it has been previously defined with anexplicitly specified or modeled DEFINE attribute.REUSESpecifies that the cluster can be opened again and again as a reusablecluster. When a reusable cluster is opened, its high-used RBA is set to zeroif you open it with an access control block that specifies the RESETattribute.REUSE lets you create an entry-sequenced, key-sequenced, or relativerecord work file.When you create a reusable cluster, you cannot build an alternate index tosupport it. Also, you cannot create a reusable cluster with key ranges (seethe KEYRANGE parameter). Reusable data sets can be multivolume andcan have up to 123 physical extents.Restriction: If you select REUSE and your command also contains thekeyword UNIQUE, you must remove the UNIQUE keyword or theDEFINE command will be unsuccessful.Abbreviation: RUSNOREUSEIndicates that the cluster cannot be opened again as a new cluster.Abbreviation: NRUSSHAREOPTIONS(crossregion[ crosssystem]|1 3)Shows how a component or cluster can be shared among users. However,SMS-managed volumes, and catalogs containing SMS-managed data sets, mustnot be shared with non-SMS systems. For a description of data set sharing, seez/OS DFSMS: Using Data Sets. To ensure integrity, you should be sure thatshare options specified at the DATA and INDEX levels are the same.The value of SHAREOPTIONS is assumed to be (3,3) when the data set isaccessed in VSAM RLS or DFSMStvs mode.crossregionSpecifies the amount of sharing allowed among regions within the samesystem or within multiple systems using global resource serialization(GRS). Independent job steps in an operating system, or multiple systemsin a GRS ring, can access a VSAM data set concurrently. For moreinformation about GRS, see z/OS MVS Planning: Global ResourceSerialization. To share a data set, each user must use DISP=SHR in the dataset’s DD statement. You can use the following options:OPT 1 The data set can be shared by any number of users for readprocessing, or the data set can be accessed by only one user forread and write processing. VSAM ensures complete dataintegrity for the data set. This setting does not allow anynon-RLS access when the data set is already open for VSAMRLS or DFSMStvs processing. A VSAM RLS or DFSMStvs openwill fail with this option if the data set is already open for anyprocessing.OPT 2 The data set can be accessed by any number of users for readprocessing, and it can also be accessed by one user for writeprocessing. It is the user’s responsibility to provide read162 z/OS V1R6.0 DFSMS Access Method Services for Catalogs