Defining a VSAM Data Set

You define a VSAM data set by using the IBM Access Method Services (AMS) IDCAMS utility, which is invoked from JCL. The following example uses IDCAMS to delete, allocate, and define a KSDS, an RRDS, and an ESDS. Note that the IDCAMS DEFINE parameters are generally self-explanatory by name. Make special note of the parameters RECORDSIZE (average maximum) and KEYS (length offset), where the keys offset is relative to the beginning of the record.

//VSAMDEF JOB job information
//DEFINE EXEC PGM=IDCAMS
//SYSPRINT  DD SYSOUT=A
//SYSIN     DD *

  DELETE (dsname.K1719) PURGE CLUSTER
  DEFINE CLUSTER (NAME(dsname.K1719) INDEXED VOLUMES(xxxxxx) -
         TRACKS(1) KEYS(17 19) RECORDSIZE(40 110) NONSPANNED) -
         DATA (NAME(dsname.K1719.DATA)) INDEX (NAME(dsname.K1719.INDEX))

  DELETE (dsname.R002) PURGE CLUSTER
  DEFINE CLUSTER (NAME(dsname.R002) NUMBERED VOLUMES(xxxxxx) TRACKS(1) -
         RECORDSIZE(120 120) NONSPANNED) DATA (NAME(dsname.R002.DATA))

  DELETE (dsname.E002) PURGE CLUSTER
  DEFINE CLUSTER (NAME(dsname.E002) NONINDEXED VOLUMES(xxxxxx) -

         TRACKS(1) RECORDSIZE(80 80)) DATA (NAME(dsname.E002.DATA))
/*
//

If the VSAM data sets do not already exist, this example produces a return code of 8 for the DELETE operation.

You can also define a VSAM data set in two other ways:

The VSAMLOAD System Option and VSAMUPDATE System Option are necessary for loading and updating VSAM data sets.

The following is an example of a macro variable:

options vsamload vsamupdate;

   /* Delete the cluster if it exists. */
x "delete ('dsname.esds.student') purge cluster";

   /* Build a macro variable containing the commands */
   /* that define a VSAM ESDS.                       */

%let def=%str(define cluster %(name('dsname.esds.student') );
%let def=&def %str(records(10 5) );
%let def=&def %str(recsz(90 90) );
%let def=&def %str(shareoptions(2,3) );
%let def=&def %str(volumes( xxxxxx ) );
%let def=&def %str(reuse );
%let def=&def %str(cisz(2048) );
%let def=&def %str(nonindexed %) );

   /* Submit the macro variable for execution. */
%sysexec &def;
run;

The example defines an ESDS that is named dsname.ESDS.STUDENT. If the ESDS already exists, this example deletes the data set and redefines it. The necessary SAS system options VSAMLOAD and VSAMUPDATE are included in the beginning of the example. The first qualifier of the data set name, dsname, represents a value that the user supplies.

The following is an example of a TSO DEFINE command:

X  DEFINE CLUSTER
      (
       NAME('dsname.TEST.VSAMFILE.CLUSTER')
       VOLUME(xxxxxx)
       TRACKS(5,1)
       CONTROLINTERVALSIZE(4096)
       FREESPACE(10,20)
       KEYS(4,0)
       RECORDSIZE(80,80)
      )
   DATA
      (
       NAME('dsname.TEST.VSAMFILE.DATA')
      )      
   INDEX 
      (
       NAME('dsname.TEST.VSAMVILE.INDEX')
       CONTROLINTERVALSIZE(1024)
      )
  ;