COBOL Std 8 Data Definition Rules

8. Data Definition Rules

8.1 Numeric Usage

• Signed arithmetic fields must use the S prefix: PIC S9(9).
• Packed-decimal (COMP-3) is the preferred internal numeric type for arithmetic fields — smaller footprint and faster on most platforms.
• Binary (COMP-5) for SQL Communications Area fields (SQLCODE etc.) to match GixSQL generated C types.
• DISPLAY numeric only for print-output or host-variable character-format copybooks.

Use Case	Recommended PIC	Notes
Integer counter	S9(9) COMP-3	Handles values to ±999,999,999.
Currency / amount	S9(9)V99 COMP-3	Odd digit count for packed efficiency.
Square root / remainder	9(9)V9(9) DISPLAY	18-digit decimal for precision comparisons.
DB identity / sequence	S9(9) COMP-3	Match PostgreSQL INTEGER type.
SQLCODE / SQLERRD	S9(9) COMP-5	Required by GixSQL SQLCA layout.

8.2 88-Level Condition Names

• Define 88-level conditions for every significant state a field can hold; never test magic numbers directly in procedural code.
• 88-level names must be self-documenting: SW-END-OF-FILE rather than SW-FLAG-1.
• Comment the business meaning of each 88 at its definition.

<syntaxhighlight lang="cobol">

      03 DAL-RESULT            PIC 9(2) VALUE ZERO.
         *-- 0 = operation succeeded
         88 DAL-METHOD-OK      VALUE 0.
         *-- 1 = operation failed; caller should log and stop
         88 DAL-METHOD-NOK     VALUE 1.
         *-- 2 = end of data / not found; not an error
         88 DAL-METHOD-EOF     VALUE 2.

</syntaxhighlight>

8.3 Host Variable Copybooks

• SQL host variables must be defined in a dedicated copybook (suffix -TAB) included via EXEC SQL INCLUDE.
• Do not define host variables inline in WORKING-STORAGE outside a designated include.
• Character-format and packed-decimal versions are separate copybooks if both are needed; name them unambiguously (e.g. PRIMES-TAB-PKD.cpy vs PRIMES-TAB.cpy).

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