COBOL SORT Procedure: USING, GIVING, INPUT, and OUTPUT Examples

A COBOL program can sort records inside the program with the SORT statement. That is useful when the program must select records before sorting or handle sorted records one at a time after sorting. For a simple production file sort, a separate JCL DFSORT step is often easier to tune and support, but internal COBOL SORT still has a place.

Sort, then process records.

What does COBOL SORT do?

The COBOL SORT statement arranges records or table elements in a sequence defined by one or more keys. For file sorting, COBOL uses an SD sort-file description, receives records from an input file or input procedure, sorts them, and then writes them to an output file or passes them to an output procedure.

Simple SORT USING GIVING example

The simplest form uses USING for the input file and GIVING for the output file. COBOL opens, reads, writes, and closes those files as part of the SORT. IBM notes that the input and output files named in these phrases must not already be open when the SORT executes.

SELECT INPUT-FILE  ASSIGN TO INFILE.
SELECT SORT-FILE   ASSIGN TO SORTWK.
SELECT OUTPUT-FILE ASSIGN TO OUTFILE.

SD  SORT-FILE.
01  SORT-REC.
    05 SORT-ACCOUNT-NO     PIC X(10).
    05 SORT-DATE           PIC X(8).
    05 SORT-AMOUNT         PIC S9(9)V99 COMP-3.

PROCEDURE DIVISION.
    SORT SORT-FILE
       ON ASCENDING KEY SORT-ACCOUNT-NO
       USING INPUT-FILE
       GIVING OUTPUT-FILE
    GOBACK.

This form fits a direct file-to-file sort where every input record should appear in the sorted output and no custom record logic is needed inside the COBOL program.

When to use INPUT PROCEDURE

Use INPUT PROCEDURE when records must be selected, edited, or built before the sort begins. The input procedure reads or creates records and sends each accepted record to the sort file with RELEASE.

SORT SORT-FILE
   ON ASCENDING KEY SORT-ACCOUNT-NO
   INPUT PROCEDURE 2000-BUILD-SORT-RECS
   GIVING OUTPUT-FILE.

2000-BUILD-SORT-RECS.
    PERFORM UNTIL END-OF-FILE
       READ INPUT-FILE
          AT END
             SET END-OF-FILE TO TRUE
          NOT AT END
             IF IN-STATUS = 'A'
                MOVE INPUT-REC TO SORT-REC
                RELEASE SORT-REC
             END-IF
       END-READ
    END-PERFORM.

Use this pattern when the program must drop inactive records, change field layouts, or combine working-storage values before the sort sees the record.

When to use OUTPUT PROCEDURE

Use OUTPUT PROCEDURE when sorted records must be processed before they are written. The output procedure gets each sorted record with RETURN. IBM recommends coding RETURN ... AT END and running until the end condition is reached.

SORT SORT-FILE
   ON ASCENDING KEY SORT-ACCOUNT-NO
   USING INPUT-FILE
   OUTPUT PROCEDURE 3000-WRITE-REPORT.

3000-WRITE-REPORT.
    PERFORM UNTIL NO-MORE-SORT-RECS
       RETURN SORT-FILE
          AT END
             SET NO-MORE-SORT-RECS TO TRUE
          NOT AT END
             MOVE SORT-REC TO REPORT-REC
             WRITE REPORT-REC
       END-RETURN
    END-PERFORM.

This form fits sorted reports, grouped totals, break processing, and cases where the program must inspect the sorted stream before writing the final output.

RELEASE and RETURN in plain English

Statement	Where it is used	Purpose
RELEASE	Input procedure	Sends one record to the sort file before sorting starts.
RETURN	Output procedure	Gets one sorted record from the sort file after sorting finishes.
AT END	RETURN statement	Detects that no more sorted records are available.

COBOL SORT vs JCL SORT

Use internal COBOL SORT when selection, transformation, or report logic belongs naturally in the program. Use JCL SORT when the requirement is only to sort, copy, include, omit, reformat, or split files. A separate DFSORT step is usually easier for operations teams to tune because sort memory, work files, and control statements are visible in JCL.

Common mistakes

Opening files before SORT USING or GIVING

Do not open the files named in USING or GIVING before the SORT. The SORT statement handles those files for that form.

Forgetting RELEASE in the input procedure

An input procedure must release records to the sort file. If no records are released, the output procedure or output file will not receive the expected data.

Forgetting RETURN AT END

An output procedure should keep returning sorted records until the AT END condition is reached. With DFSORT, failing to reach the end condition can lead to an abnormal sort termination.

Using internal SORT for every large file

Large high-volume sorts should be reviewed carefully. If the sort can be done outside the program, a JCL SORT step may be simpler to monitor and change.

Review checklist

• Define the sort file with an SD entry.
• Choose one input path: USING or INPUT PROCEDURE.
• Choose one output path: GIVING or OUTPUT PROCEDURE.
• Use RELEASE for records passed into an input procedure.
• Use RETURN ... AT END for records pulled from an output procedure.
• Compare internal COBOL SORT with a separate DFSORT step for high-volume batch work.

Related Mainframe Forum guides

For related topics, read JCL SORT examples, SORT INREC and OUTREC examples, COBOL sequential file organization, COBOL READ statement, and COBOL PERFORM statement.

External references

IBM documents the Enterprise COBOL SORT statement, coding the output procedure, and coding the input procedure.

FAQ

What is COBOL SORT used for?

COBOL SORT arranges records or table elements by one or more keys. For files, it can take input from files or an input procedure and send sorted records to files or an output procedure.

What is INPUT PROCEDURE in COBOL SORT?

INPUT PROCEDURE runs before sorting. It selects or builds records and passes them to the sort file with RELEASE.

What is OUTPUT PROCEDURE in COBOL SORT?

OUTPUT PROCEDURE runs after sorting. It gets each sorted record with RETURN and can write, total, or report the record.

Should I use COBOL SORT or JCL SORT?

Use COBOL SORT when program logic must run before or after sorting. Use JCL SORT when the task is mainly file sorting, copying, filtering, or formatting.