mainframe-planning

Create a comprehensive transformation guide that maps each mainframe dependency to its standard COBOL replacement.

This guide is a prerequisite for the actual transformation — DO NOT modify any code, only create the guide.

Output Format

Document each mainframe-specific construct with:

1. Pattern: The mainframe construct (e.g., EXEC CICS READ FILE(...))
2. Replacement: The standard COBOL equivalent
3. Error Handling: How to replicate the mainframe's error behavior
   • Map CICS RESP/RESP2 codes to FILE STATUS equivalents
   • Specify which FILE STATUS values to check (e.g., 00=success, 23=not found, 35=file not exists)
4. Resource Cleanup: Any cleanup the replacement requires (CICS auto-manages resources; file I/O does not)
5. Edge Cases: Behavior differences between mainframe and standard COBOL

Constructs to Address

Data Operations (CICS/IMS/VSAM)

• READ, WRITE, REWRITE, DELETE operations
• STARTBR, READNEXT, READPREV (browse operations)
• CICS error handling: HANDLE CONDITION, RESP/RESP2 options
• VSAM → sequential or indexed file I/O

UI/Terminal Operations (BMS maps, screens)

• SEND MAP, RECEIVE MAP → these can be MOCKED or stubbed
• Screen I/O is not needed for business logic validation
• Document how to replace with simple ACCEPT/DISPLAY or test harness stubs
• Focus on preserving the data flow, not the UI interaction

Other Mainframe Constructs

• Mainframe data types (COMP-3 packed decimal, etc.)
• JCL-embedded constructs
• IMS calls (if present)

Critical Requirements

• Every CICS command that can fail MUST have an error handling replacement documented
• UI operations should be clearly marked as "mock/stub" so the agent doesn't get stuck on them
• Prefer: file-based I/O over mainframe I/O, standard data types over mainframe types

Common Mappings Reference

FILE STATUS Codes

CICS to Standard COBOL