COBOL

COBOL runs 70% of the world’s business transactions. Modern COBOL (GnuCOBOL 3.2 / IBM Enterprise COBOL) supports JSON, XML, and Object-Oriented features.

When to Use

• Mainframes: The backbone of banking/insurance systems (CICS/IMS).
• Legacy Migration: Moving logic to Linux/Cloud using GnuCOBOL.
• Decimal Arithmetic: Native fixed-point math (PICTURE 9V99) is unmatched for currency.

Core Concepts

Divisions

IDENTIFICATION, ENVIRONMENT, DATA, PROCEDURE.

Picture Clause

01 SALARY PIC 9(5)V99. Defines data layout precisely.

PERFORM

The main control flow loop.

Best Practices (2025)

Do:

• Use GnuCOBOL: For local development on Mac/Linux.
• Use VS Code: With the bitlang.cobol extension.
• Unit Test: Use COBOL Check or ZUnit.

Don’t:

• Don’t use GO TO: Use PERFORM and structured programming.

References

• GnuCOBOL FAQ