Using COBOL's EVALUATE for Clean Multi-Way Branching
Learn how COBOL's EVALUATE statement replaces nested IFs with a clear, range‑capable multi‑way branch, illustrated by a status‑code‑to‑benefit example.
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cobolDebugging Syntax Errors and Undefined Variables in Rexx
A diagnostic guide for resolving Syntax Errors and Undefined Variable issues in Rexx, featuring a diagnostic matrix, tracing techniques, and initialization fixes.
rexxReliable Date Arithmetic in COBOL Using DATE-OF-INTEGER and INTEGER-OF-DATE
Learn how COBOL programmers can add or subtract days safely with the standard intrinsic functions DATE-OF-INTEGER and INTEGER-OF-DATE, avoiding manual leap‑year logic.
Embedded SQL in COBOL: Minimal Design, Trust Boundaries, and Operational Safeguards
Embedded SQL lets COBOL programs access DB2 directly, but you must design for trust boundaries, operational checks, and failure modes. This article outlines a minimal architecture, sample code, and when to consider redesigning.
Preventing duplicate writes during CICS transaction retries
In a COBOL application running under CICS, maintaining data integrity during transaction retries is critical. While the use of sync-points and the EXEC CICS SYNCPOINT command ensures that a Logical Unit of Work (LUW) is processed atomically, the system does not natively track whether a specific business event has already been persisted if the transaction is
WRITE with uniqueness check vs REWRITE for idempotent record handling
Ensuring Idempotency in Indexed File Writes When implementing retry logic for data persistence in COBOL, preventing duplicate records is critical. In environments using indexed files, developers must decide between two primary patterns to handle potential retries without duplicating writes. One approach utilizes the WRITE statement combined with a manual che
File Status 35 during OPEN statement in mainframe environments
In IBM Enterprise COBOL, the OPEN statement relies on the external Job Control Language (JCL) to map the SELECT clause's assignment name to a physical dataset via a Data Definition (DD) statement. When the runtime environment cannot locate the required DD name or the associated dataset is missing, the system returns a File Status 35. While this is a document
COBOL Data Division REDEFINES mapping for zero-downtime migration
Migrating a legacy COBOL application to a modern schema without downtime requires a shadowing strategy where data is dual-written to both the legacy mainframe and a target system. A primary challenge involves the REDEFINES clause in the Data Division, which allows a single memory area to be interpreted as multiple distinct data structures. While sequential f