Specifying relative organization for VSAM files
Identify VSAM RRDS files in a COBOL program by using the
IS RELATIVE clause. Use the
RELATIVE KEY IS clause
to associate each logical record with its relative record number.
The following example shows a relative-record data set (RRDS) that is accessed randomly by the value in the relative key:
ASSIGN TO RELATIVE-FILE
ORGANIZATION IS RELATIVE
ACCESS IS RANDOM
RELATIVE KEY IS RFILE-RELATIVE-KEY
FILE STATUS IS FSTAT-CODE VSAM-CODE.
You can use a randomizing routine to associate a key value in each record with the relative record number for that record. Although there are many techniques to convert a record key to a relative record number, the most commonly used is the division/remainder technique. With this technique, you divide the key by a value equal to the number of slots in the data set to produce a quotient and remainder. When you add one to the remainder, the result is a valid relative record number.
Alternate indexes are not supported for VSAM RRDS.