Mainframe Removal

Apply the transformations from a transformation guide to convert mainframe-specific COBOL to standard COBOL.

Prerequisite: A transformation guide must exist (see cobol-mainframe-planning skill).

Transformation Requirements

Data Operations

• Replace each CICS/VSAM construct with its standard COBOL equivalent per the plan
• Add FILE STATUS checks after EVERY file operation:
  • Check for success (00) before proceeding
  • Handle "not found" (23) distinctly from I/O errors (3x)
  • Handle "file not exists" (35) at OPEN time
• Add explicit CLOSE statements in all code paths (including error paths)

UI/Terminal Operations (BMS maps, SEND/RECEIVE)

• Replace with simple stubs or ACCEPT/DISPLAY statements
• Do NOT spend time replicating screen layouts
• Focus on preserving data flow, not UI fidelity

Error Handling

• Replace CICS RESP/RESP2 checks with equivalent FILE STATUS logic
• Replace HANDLE CONDITION with explicit status checking after operations
• Ensure error paths don't leave files open

See references/cics-transformation-examples.md for before/after code examples.

Verification

After transformation:

• Code MUST compile without errors
• Test with valid input → should execute core business logic
• Test with missing/invalid files → should fail gracefully, not crash

Preserve

• All original business logic
• Data transformations and calculations
• Validation rules

Checklist

• All EXEC CICS commands replaced
• FILE STATUS declared for all files
• FILE STATUS checked after every I/O operation
• CLOSE statements in all code paths
• Code compiles successfully
• Basic test execution passes