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

Code	Meaning	CICS Equivalent
00	Success	Normal completion
23	Record not found	NOTFND condition
35	File does not exist	NOTOPEN condition
22	Duplicate key	DUPREC condition
3x	I/O errors	Various IOERR conditions

CICS to Standard COBOL

CICS Command	Standard COBOL
EXEC CICS READ FILE(...)	READ filename INTO...
EXEC CICS WRITE FILE(...)	WRITE record-name FROM...
EXEC CICS REWRITE FILE(...)	REWRITE record-name FROM...
EXEC CICS DELETE FILE(...)	DELETE filename RECORD
EXEC CICS STARTBR FILE(...)	START filename KEY...
EXEC CICS READNEXT FILE(...)	READ filename NEXT INTO...