SORT

            The programming SORT is called as internal sort whereas the sort in JCL is called external sort. If you want to manipulate the data before feeding to sort, prefer internal sort. In all other cases, external sort is the good choice. Internal sort, in turn invokes the SORT product of your installation. (DFSORT). In the run JCL, allocate at least three sort work files. (SORT-WKnn => nn can be 00-99). 

FASTSRT compiler option makes the DFSORT to do all file I-O operation than your COBOL program. It would significantly improve the performance. The result of the SORT can be checked in SORT-RETURN register. If the sort is successful, the value will be 0 else 16.

Syntax:

SORT SORTFILE ON ASCENDING /DESCENDING KEY sd-key-1 sd-key2

  USING file1 file2 / INPUT PROCEDURE IS section-1

  GIVING file3       / OUTPUT PROCEDURE is section-2

END-SORT

File1, File2 are to-be-sorted input files and File3 is sorted-output file and all

of them are defined in FD.SORTFILE is Disk SORT Work file that is defined at SD. It should not be explicitly opened or closed.

INPUT PROCEDURE and USING are mutually exclusive. If USING is used, then file1 and files should not be opened or READ explicitly. If INPUT PROCEDURE is used then File1 and file2 need to be OPENed and READ the records one by one until end of the file and pass the required records to sort-work-file using the command RELEASE.

Syntax: RELEASE sort-work-record from input-file-record.

OUTPUT Procedure and GIVING are mutually exclusive. If GIVING is used, then file3 should not be opened or WRITE explicitly. If OUTPUT procedure is used, then File3 should be OPENed and the required records from sort work file should be RETURNed to it. Once AT END is reached for sort-work-file, close the output file.

Syntax: RETURN sort-work-file-name AT END imperative statement.

Program sort registers (and its equivalent DFSORT parameter/meaning)

SORT-FILE-SIZE (FILSZ), SORT-CORE-SIZE (RESINV), SORT-MSG(MSGDDN)

SORT-MODE-SIZE (SMS=nnnnn)

SORT-RETURN(return-code of sort) and

SORT-CONTROL (Names the file of control card – default is IGZSRTCD