Finalization - Cleanup process

Key Characteristics

• • Resource Release: Involves freeing up resources such as DD allocations, GETMAINed storage, ENQued resources, VSAM buffers, and CICS storage areas that were acquired during execution.
  • File Closure: Ensures that all opened datasets (sequential, VSAM, PDS/PDSE members) are properly closed, flushing any buffered data to disk and updating dataset control blocks.
  • Trigger Mechanisms: Can be explicitly coded within application programs (e.g., CLOSE statements in COBOL, FREE in C), automatically handled by the operating system (z/OS) upon task termination, or managed by subsystems like CICS or IMS at transaction or program end.
  • Normal vs. Abnormal Termination: Cleanup routines must be robust enough to handle both successful completion and abnormal termination (abend), often requiring specific ESTAE or FRR routines to ensure critical resources are released even during failures.
  • Scope: The scope of cleanup can range from an individual program's resources to an entire batch job's resources, or a CICS transaction's resources, depending on the context.

Use Cases

• • Batch Job Completion: After a COBOL or PL/I batch program finishes, the operating system (z/OS) performs cleanup for all DD statements defined in the JCL, releasing datasets and devices. Application code also explicitly closes files and frees dynamically allocated storage.
  • CICS Transaction Termination: When a CICS transaction completes, CICS automatically releases storage acquired via GETMAIN (unless specified otherwise), closes VSAM files, and frees other CICS-managed resources associated with that transaction.
  • DB2 Utility Execution: After a DB2 utility (e.g., REORG, COPY) finishes, it performs internal cleanup to release DB2 locks, close dataset connections, and update catalog information, ensuring data integrity.
  • IMS Program Termination: An IMS application program, upon issuing a TERM call or reaching its end, triggers IMS to release program-specific resources, such as PCBs and GSAM datasets, and to commit database changes.

Related Concepts