Modernization Hub

Guideline - Recommended Practice

Enhanced Definition

In the mainframe context, a guideline or recommended practice refers to a set of established principles, procedures, or conventions that, while not strictly mandatory, are advised for optimal performance, reliability, security, maintainability, or efficiency in z/OS environments. These practices are often derived from industry experience, IBM recommendations, or internal organizational standards.

Key Characteristics

    • Non-mandatory: Unlike strict rules or syntax requirements, guidelines offer advice rather than enforcement, though deviation may lead to sub-optimal outcomes.
    • Context-specific: Practices are often tailored to specific mainframe components like JCL, COBOL, CICS, DB2, IMS, or system administration tasks.
    • Evolves with technology: As z/OS and related products evolve, so do the recommended practices to leverage new features or address new challenges.
    • Aids in standardization: Following guidelines promotes consistency across development teams, making code and configurations easier to understand and maintain.
    • Improves system health: Adherence often leads to better resource utilization, reduced errors, improved security posture, and enhanced system stability.
    • Documented: Typically found in official IBM documentation, internal standards manuals, or industry whitepapers.

Use Cases

    • COBOL Program Development: Guidelines for coding style, variable naming conventions, error handling, FILE STATUS checking, and PERFORM statement usage to ensure maintainability and performance.
    • JCL Job Stream Design: Recommended practices for DD statement allocation, STEP ordering, RESTART parameters, DISP processing, and PROC usage to optimize job execution and recovery.
    • CICS Transaction Design: Guidelines for EXEC CICS command usage, storage management, abend handling, and transaction isolation to ensure high availability and responsiveness.
    • DB2 SQL Query Optimization: Best practices for indexing, JOIN operations, WHERE clause construction, and RUNSTATS execution to improve database performance.
    • System Administration: Recommendations for SMF data collection, IPL procedures, security hardening (RACF), and performance tuning (WLM) to maintain a healthy z/OS system.

Related Concepts

Guidelines are foundational to governance and standards within a mainframe enterprise. They inform the creation of coding standards, JCL standards, security policies, and operational procedures. They often stem from IBM Redbooks or IBM Redpapers, which provide in-depth technical recommendations, and are enforced through code reviews, audits, and automated scanning tools that check for adherence to these practices.

Best Practices:
  • Regularly review and update: Ensure guidelines remain current with z/OS releases, product updates, and evolving business requirements.
  • Document clearly and concisely: Make guidelines easily accessible and understandable for all relevant personnel, including examples.
  • Educate and train teams: Provide ongoing training for developers and system programmers on the rationale and application of recommended practices.
  • Automate enforcement where possible: Utilize tools like static code analyzers or JCL checkers to automatically identify deviations from established guidelines.
  • Foster a culture of adherence: Encourage teams to understand the benefits of following guidelines for system stability, performance, and maintainability.

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