EIRR - Enhanced IMS Resource Reader

Enhanced Definition

EIRR (Enhanced IMS Resource Reader) is an IBM-supplied batch utility for z/OS that reads and formats various IMS control blocks and resource definitions, such as Database Descriptors (DBDs), Program Specification Blocks (PSBs), and Application Control Blocks (ACBs). Its primary purpose is to provide detailed, human-readable reports of IMS resource definitions, aiding in troubleshooting, analysis, and documentation within the mainframe environment. EIRR (Enhanced IMS Resource Reader) is an IBM utility designed to read, analyze, and report on the definitions of IMS (Information Management System) resources. It processes IMS control blocks and resource libraries to provide detailed information about databases, program specifications, transactions, and other IMS components, aiding in system management and problem determination.

Key Characteristics

- IBM-supplied Utility: EIRR is an official IBM product, part of the IMS utilities, ensuring compatibility and reliability within the z/OS environment for managing IMS resources.
- Batch Execution: It operates as a standard z/OS batch job, typically invoked via JCL, allowing for automated and scheduled analysis of IMS resources without requiring online IMS system availability.
- Comprehensive Reporting: EIRR can generate various reports detailing the structure and attributes of IMS databases (from DBDs), application program views (from PSBs), and the combined access blocks (from ACBs).
- Input Sources: It reads input from IMS libraries like IMSDALIB (for DBDs, PSBs) and ACBLIB (for ACBs), as well as from IMS log records or specific data sets containing control block information.
- Diagnostic Aid: Provides critical information for diagnosing issues related to IMS database corruption, application program access, or performance bottlenecks by exposing the underlying resource definitions.
- Customizable Output: Users can specify various control statements and options (e.g., TYPE=, DBD=, PSB=) to tailor the output reports, focusing on specific resources or levels of detail.

Use Cases

- Troubleshooting Application Errors: Analyzing PSB definitions to verify segment sensitivity, processing options, or field access when an IMS application encounters unexpected behavior or abends.
- Database Structure Verification: Examining DBD reports to confirm physical database layouts, segment hierarchies, field definitions, and indexing schemes after database changes or for auditing purposes.
- Post-ACBGEN Validation: Running EIRR against the newly generated ACBLIB to ensure that the DBDs and PSBs were correctly assembled and linked into the Application Control Blocks.
- System Documentation: Generating comprehensive reports of all active IMS resource definitions for system documentation, compliance audits, or knowledge transfer among mainframe teams.
- Performance Tuning: Reviewing DBD and PSB definitions to identify potential inefficiencies in database design or application access patterns that could impact IMS transaction performance.

Related Concepts

EIRR is intrinsically linked to IMS (Information Management System), specifically its database and transaction management components. It directly interacts with IMS control blocks like DBDs (Database Descriptors), which define the physical structure of IMS databases, and PSBs (Program Specification Blocks), which define an application program's view of one or more databases. It also processes ACBs (Application Control Blocks), which are the runtime representations of DBDs and PSBs, created by the ACBGEN utility. EIRR provides a crucial tool for understanding and validating the definitions created by IMS system programmers and database administrators, complementing other IMS utilities like DBDGEN, PSBGEN, and ACBGEN.

Best Practices:

Regular Documentation: Incorporate EIRR into your routine for documenting IMS database and application definitions, especially after significant changes, to maintain up-to-date system documentation.
Automated Validation in Change Management: Integrate EIRR job steps into your change management processes for IMS resource definitions (DBDs, PSBs, ACBs) to automatically validate the integrity and correctness of new