Feature

Enhanced Definition

In the context of IBM mainframe systems and z/OS, a **feature** refers to a distinct capability, function, or enhancement provided by an operating system component, a program product (like CICS, DB2, IMS), or an application. These features extend the system's functionality, improve performance, enhance security, or streamline operations for enterprise workloads.

Key Characteristics

- Product-Specific: Features are typically integral to a specific IBM program product (e.g., z/OS, CICS Transaction Server, DB2 for z/OS) or an Independent Software Vendor (ISV) product, often documented in its respective manuals.
- Delivery Mechanisms: New features are introduced through new product releases, version upgrades, or via Program Temporary Fixes (PTFs) and APARs (Authorized Program Analysis Reports) that enable new functionality.
- Configuration Dependent: Many features require explicit configuration, activation, or parameter settings (e.g., in SYS1.PARMLIB members, CICS SIT parameters, DB2 DSNZPARM macro) to be enabled and utilized.
- Resource Impact: Implementing or activating a feature may have implications for system resources such as CPU, memory (real and virtual storage), I/O, or disk space, requiring careful planning and monitoring.
- Backward Compatibility: While new features enhance capabilities, they are often designed with consideration for backward compatibility to minimize disruption to existing applications and configurations.

Use Cases

- Enabling a new security capability: Activating a new RACF (Resource Access Control Facility) feature to support multi-factor authentication for z/OS logon or specific resource access.
- Leveraging performance enhancements: Configuring DB2 for z/OS to use a new query optimization feature introduced in a recent version to improve database transaction response times.
- Implementing new language constructs: Utilizing a new COBOL language feature (e.g., intrinsic functions, object-oriented extensions, JSON PARSE/GENERATE) to modernize existing business applications.
- Activating workload management policies: Enabling a new WLM (Workload Manager) feature in z/OS to dynamically adjust resource allocation based on business priorities and service level objectives.
- Integrating with external systems: Using a new CICS Transaction Server feature to facilitate secure communication with cloud-based APIs via z/OS Connect Enterprise Edition.

Related Concepts

Features are the building blocks of IBM program products and z/OS itself, directly impacting the capabilities of subsystems like CICS, DB2, and IMS. They are often delivered as part of PTFs or new product releases, which are managed through SMP/E (System Modification Program/Extended) for installation and maintenance. Understanding features is crucial for system programmers who configure PARMLIB members, JCL procedures, and subsystem parameters to tailor the mainframe environment and optimize system performance.

Best Practices:

Thorough Documentation Review: Always consult the official IBM documentation (e.g., IBM Knowledge Center, product manuals) to understand a feature's purpose, configuration requirements, and potential impacts.
Staged Implementation: Test new features extensively in a non-production environment (e.g., development, QA LPAR) before deploying them to production to identify and mitigate