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

DEFINE CLUSTERwhere:v MAXLRECL is the maximum spanned record size.v CI/CA represents the number of control intervals per control area.v CA is the number of control areas.v CISZ is the control interval size.When you select NUMBERED, you identify a data set as a relative record dataset. If you use NUMBERED and select the same value for average as formaximum, the relative records must be fixed-length. If you specifyNUMBERED and select two different values for the average and maximumrecord sizes, the relative records can be variable-length. If you know that yourrelative records are fixed-length, however, be sure to define them asfixed-length. Performance is affected for relative record data sets defined asvariable-length. Each variable-length relative record is increased internally inlength by four.When your records are fixed length, you can use the following formula to finda control interval size that contains a whole number (n) of records:CISZ = (n x RECSZ) + 10orn = (CISZ - 10)RECSZIf you select SPANNED or NUMBERED for your fixed-length records:CISZ =(n x (RECSZ + 3)) + 4orn = (CISZ - 4)(RECSZ + 3)where:vvn is the number of fixed-length records in a control interval.CISZ is the control interval size (see also the CONTROLINTERVALSIZEparameter).v RECSZ is the average record size.defaultWhen SPANNED is used, the default is RECORDSIZE(4086 32600).Otherwise, the default is RECORDSIZE(4089 4089).Example:REC(sec) x RECSZ(avg) > RECSZ(max)where:– REC(sec) is the secondary space allocation quantity, in records.– RECSZ(avg) is the average record size (default = 4086 or 4089 bytes).– RECSZ(max) is the maximum record size (default = 4089 or 32600 bytes).When the SPANNED record size default prevails (32600 bytes), the secondaryallocation quantity should be at least 8 records.Restriction: With REPRO and EXPORT, you cannot use data sets with recordsizes greater than 32 760.Abbreviation: RECSZREUSE|NOREUSESpecifies whether or not the cluster can be opened again and again as areusable cluster.Chapter 14. DEFINE CLUSTER 161