CICS-Sequential and Random Access

Not only in CICS, in any of the mainframe Technologies, reading of the files can be done in multiple ways.

Especially in CICS, Sequential and Random access are most popular ways of reading files.

Sequential Access: STARTBR (start browse) keeps record at the key position, from where we want to read a record.

READNEXT-will actually read the record into working storage file description area.

Sample syntax:

EXEC CICS STARTBR
   DATASET('FILEAA')
   RIDFILD(REC-IO-KEY)==> Record Key
  GTEQ
END-EXEC.

—-

EXEC CICS READNEXT
   DATASET('FILEAA')
    INTO(FILE-IO-AREA) ==working storage file description at '01' level
   RIDFILD(REC-IO-KEY)==>Record Key
   GTEQ
END-EXEC.

Random Access: File reading by this way will be achieved with “READ” command. It reads the record, as per key mentioned, and moves into working storage record area.

Sample syntax:

EXEC CICS READ
   DATASET('FILEAA')
    INTO(FILE-IO-AREA) ==working storage file description at '01' level
   RIDFILD(REC-IO-KEY)==>Record Key
   GTEQ
END-EXEC.

These may look simple, but, many people do not have much idea. I am sure it will help you.

In my next posts, I will give how data will be retrieved by using DB2 and IMSDB.