Secondary index

You must define one Secondary index for each data store and initialize it with a header record.

This is an example of JCL for the scratch and creation of the secondary index file: 
//DELSKI   EXEC PGM=IDCAMS
//SYSPRINT DD SYSOUT=*
           DELETE OPCDEV.SKI0X CLUSTER PURGE
//*----------------------------------------------------------------
//DEFSKI   EXEC PGM=IDCAMS
//SYSPRINT DD   SYSOUT=*
//SYSIN    DD *
           DEFINE CLUSTER(NAME(OPCDEV.SKI0X)-
           CYLINDERS(2,1)-
           VOLUMES(S25PRA)-
           KEYS(40,0)-
           RECORDSIZE(76,32000)-
           CISZ(4096)-
           UNIQUE-
           INDEXED-
           SHR(1,3)-
           FREESPACE(10,10))