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

uffer. A routine or storage used to compensate for adifference in rate of flow of data, or time of occurrenceof events, when transferring data from one device toanother.BWO.CCA.See backup-while-openSee control areacache set. A parameter on storage class and defined inthe base configuration information that maps a logicalname to a set of CF cache structure names.cache set. A parameter on storage class and defined inthe base configuration information that maps a logicalname to a set of CF cache structure names.capacity planning. The process of forecasting andcalculating the appropriate amount of physicalcomputing resources required to accommodate anexpected workload.Cartridge System Tape. The base tape cartridge mediaused with 3480 or 3490 Magnetic Tape Subsystems.Contrast with Enhanced Capacity Cartridge System Tape.catalog. A data set that contains extensive informationrequired to locate other data sets, to allocate anddeallocate storage space, to verify the access authorityof a program or operator, and to accumulate data setusage statistics. See master catalog and user catalog.catalog cleanup. A process that allows the deletion ofentries if their volume is no longer available; catalogcleanup also allows deletion of a catalog even though itis not empty. Catalog cleanup is a function of theDELETE command.catalog connector. A catalog entry, called either a usercatalog entry or a catalog connector entry, in the mastercatalog that points to a user catalog’s volume (that is, itcontains the volume serial number of the direct accessvolume that contains the user catalog).catalog recovery area (CRA). An entry-sequenced dataset that exists on each volume owned by a recoverablecatalog, including the volume on which the catalogresides. The CRA contains copies of the catalog’srecords and can be used to recover a damaged catalog.CCSID.See coded character set identifiercell. (1) An occurrence of information such aspasswords, volume information, or associations. (2) Asingle cartridge storage location within a 3495.CF.CI.CICS.See coupling facilitySee control intervalCustomer Information Control System.class (SMS).See SMS class.class transition. An event that brings about change toan object’s service-level criteria, causing OAM toinvoke ACS routines to assign a new storage class ormanagement class to the object.cluster. In VSAM, a named structure consisting of agroup of related components. For example, when thedata is key-sequenced, the cluster contains both thedata and the index components; for data that isentry-sequenced, the cluster contains only a datacomponent.cluster entry. A catalog entry that containsinformation about a key-sequenced or entry-sequencedVSAM cluster: ownership, cluster attributes, and thecluster’s passwords and protection attributes. Akey-sequenced cluster entry points to both a data entryand an index entry. An entry-sequenced cluster entrypoints to a data entry only.Coded Character Set Identifier (CCSID). A 16-bitnumber that identifies a specific encoding schemeidentifier, character set identifiers, code page identifiers,and additional coding required information. The CCSIDuniquely identifies the coded graphic characterrepresentation used.collection. A group of objects that typically havesimilar performance, availability, backup, retention, andclass transition characteristics. A collection is used tocatalog a large number of objects which, if catalogedseparately, could require an extremely large catalog.commit. In DB2, to cause all changes that have beenmade to the database file since the last commitmentoperation to become permanent, and the records to beunlocked so they are available to other users. InDFSMStvs, a request to make all changes to recoverableresources permanent since the last commit or backoutor, for the first unit of recovery, since the beginning ofthe application.communications data set (COMMDS). The primarymeans of communication among systems governed bya single SMS configuration. The COMMDS is a VSAMlinear data set that contains the name of the ACDS andcurrent utilization statistics for each system-managedvolume, which helps balance space among systemsrunning SMS. See also active control data set and sourcecontrol data set.compaction.See improved data recording capability.compatibility mode. The mode of running SMS inwhich no more than eight names—representingsystems, system groups, or both—are supported in theSMS configuration.component. (1) A named, cataloged collection ofstored records. A component, the lowest member of thehierarchy of data structures that can be cataloged,Glossary 515