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zCOBOL SORT

Zane Hambly, December 2025. Per FIPS PUB 21-2, Section XI.

SORT.MAC has said MNOTE 8,'SORT NOT SUPPORTED YET' since November 2008. Seventeen years is a long time to leave records unsorted. The stub has been replaced with a working implementation that parses the COBOL SORT statement and generates HLASM targeting the existing z390 ZSORT infrastructure (SVC X'A1').

Both USING/GIVING and INPUT/OUTPUT PROCEDURE forms are supported. Multi-key sorts with mixed ASCENDING/DESCENDING work. MERGE does not, but Rome wasn't built in a day and neither was COBOL.

How It Works

The SORT macro parses the statement at assembly time, looks up the SD (Sort Description) entry to find record layout and key positions, then calls GEN_SORT.MAC to emit the actual HLASM. The generated code delegates to ZSORT, which does the heavy lifting via SVC X'A1'.

For INPUT/OUTPUT PROCEDURE, the macro generates PERFORM-style branch logic around the user's procedure sections. RELEASE writes records into the sort, RETURN reads them back out.

COBOL source --> SORT.MAC (parse) --> ZC_SD_FIND (lookup) --> GEN_SORT (emit) --> ZSORT (SVC)

Files

File What It Does
zcobol/mac/SORT.MAC Parses SORT statement — replaces the 2008 stub
zcobol/mac/GEN_SORT.MAC Generates HLASM code targeting ZSORT
zcobol/mac/ZCSD.MAC Parses SD entries, stores sort file metadata
zcobol/mac/ZC_SD_FIND.MAC Looks up sort files by name
zcobol/cpy/ZC_SD.CPY Global variables for sort file tracking
zcobol/mac/RELEASE.MAC Implements RELEASE for INPUT PROCEDURE
zcobol/mac/RETURN.MAC Extended to support SORT RETURN

ZC_WS.CPY was intentionally left alone. Touching shared copybooks to add sort variables felt like defusing a bomb with a hammer.

Key Type Mapping

COBOL PIC types map to ZSORT key types:

COBOL PIC ZSORT Notes
X, A CH EBCDIC character
9 (DISPLAY) ZD Zoned decimal
9 COMP-3 PD Packed decimal
9 COMP (H/F/G) FI Signed binary

File Encoding

SORT expects EBCDIC internally. For LINE SEQUENTIAL files, z390 handles ASCII-EBCDIC translation automatically. For fixed-record files, you need EBCDIC input or your output will be sorted with great confidence and zero correctness.

Limitations

Not yet implemented (flagged via MNOTE 4 at assembly time):

  • WITH DUPLICATES IN ORDER
  • COLLATING SEQUENCE IS
  • Multiple USING/GIVING files
  • MERGE statement

Tests

Test Covers
zcobol/tests/SORTASC.CBL LINE SEQUENTIAL, ascending, USING/GIVING
zcobol/tests/SORTDEF.CBL Default file organisation (no explicit ORGANIZATION)
zcobol/tests/SORTMULT.CBL Multiple SORTs in one programme (ASC then DESC)

All tests use DD name environment variables for file assignment, consistent with JCL conventions. Output is compared against .TF2 reference files:

export INFILE=zcobol/tests/SORTASC.TF1
export OUTFILE=zcobol/tests/SORTASC.OUT
bash/cblclg zcobol/tests/SORTASC
diff zcobol/tests/SORTASC.OUT zcobol/tests/SORTASC.TF2

Reference

FIPS PUB 21-2 (1985), sections XI through XI-5 (Sort-Merge Module). Incorporates ANSI X3.23-1985 and ISO 1989-1985.