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

ALLOCATERECFM(V) or RECFM(VB)RECFM(VBS)BLKSIZE must be at least four bytes largerthan LRECLBLKSIZE must be at least eight bytes.v For input or update processing, the block size must conform to the currentlydefined record length. The BLKSIZE given when the data set was created isthe default. However, you can use any BLKSIZE if it conforms to the recordlength definition.BUFL(buffer-length)The length, in bytes, of each buffer in the buffer pool. Substitute a decimalnumber for buffer-length. The number must not exceed 32,760. If you omit thisparameter and the system acquires buffers automatically, the BLKSIZE andKEYLEN parameters supply the information needed to establish buffer length.BUFNO(number-of-buffers)The number of buffers that are assigned for data control blocks. Substitute adecimal number for number-of-buffers. The number must never exceed 255.You can be limited to a smaller number of buffers depending on the limitestablished when the operating system was generated. The following showshow to get a buffer pool and the action required:MethodBUILD macro instructionGETPOOL macro instructionActionYou must use BUFNOThe system uses the number that you assignfor GETPOOLAutomatically with BPAM, BSAMYou must use BUFNOAutomatically with QSAM You can omit BUFNO and accept two buffersBUFOFF({block-prefix-length|L})Defines the buffer offset. The block-prefix-length must not exceed 99. L specifiesthe block prefix field is 4 bytes long and contains the block length.DATACLAS(data-class-name)This is the 1-to-8 character name of the data class for either SMS ornon-SMS-managed data sets. If you do not assign DATACLAS for a new dataset and the storage administrator has provided an automatic class selection(ACS) routine, the ACS routine can select a data class for the data set. If youassign DATACLAS for an existing data set, SMS ignores it. If SMS is not active,the system checks the syntax and then ignores the DATACLAS parameter.If you use the data class, you do not need to list all the attributes for a dataset. For example, the storage administrator can provide RECFM, LRECL,RECORG, KEYLEN, and KEYOFF as part of the data class definition. However,you can override the DATACLAS parameter by explicitly defining theappropriate parameters in the ALLOCATE command.The data class defines these data set allocation attributes:vvvvvData set organization:– Record organization (RECORG)– Record format (RECFM)Record length (LRECL)Key length (KEYLEN)Key offset (KEYOFF)Space allocation36 z/OS V1R6.0 DFSMS Access Method Services for Catalogs