IPLINFO - IPL Information

Enhanced Definition

`IPLINFO` is a z/OS operator command used to display crucial information about the last Initial Program Load (IPL) of the z/OS system. It provides details such as the IPL date and time, the `LOADPARM` used, and the `IEASYSxx` member that was active during system initialization. This command is vital for system administrators to verify system startup parameters and understand the current operational context.

Key Characteristics

- Operator Command: Executed from the z/OS operator console or through system management interfaces like SDSF using the D IPLINFO command.
- Displays IPL Parameters: Shows the LOADPARM value used during the last IPL, which dictates the system configuration options.
- Indicates IEASYSxx Member: Identifies the specific IEASYSxx parmlib member that was processed during NIP (Nucleus Initialization Program).
- Provides IPL Date and Time: Crucial for determining system uptime, auditing, and understanding when the system was last restarted.
- Shows CLPA Status: Indicates whether CLPA (Pageable Link Pack Area) was refreshed during the IPL, which impacts system performance and module availability.
- Non-Disruptive: It is an informational command that simply queries and displays system data without altering the system's operational state.

Use Cases

- Post-IPL Verification: System programmers use D IPLINFO immediately after an IPL to confirm that the correct LOADPARM and IEASYSxx member were used.
- Troubleshooting System Behavior: When diagnosing system-wide issues, checking the IPL parameters can help identify if a recent configuration change or an incorrect IPL option is a contributing factor.
- Auditing and Compliance: Provides historical data on system restarts, which is essential for operational logs, compliance reports, and understanding system availability.
- System Administration: Quickly ascertain when a system was last IPLed and with what core parameters, without needing to consult external logs or documentation.
- Problem Determination: Helps determine if a system was IPLed with CLPA and if that might be related to issues with updated modules in the LPA.

Related Concepts

IPLINFO is directly related to the IPL (Initial Program Load) process itself, providing a snapshot of its outcome. The LOADPARM value displayed by IPLINFO is a critical input to the IPL, determining which IEASYSxx member from SYS1.PARMLIB is used to define system-wide parameters. It also indirectly relates to NIP (Nucleus Initialization Program), as it reports on parameters that influence NIP's execution. Understanding IPLINFO output is fundamental for anyone managing z/OS system initialization and configuration, as it confirms the foundational settings of the operating system.

Best Practices:

Automated Verification: Incorporate D IPLINFO into automated post-IPL verification scripts to ensure consistency and proper system startup.
Regular Monitoring: Periodically check IPLINFO output, especially after maintenance windows or planned outages, to confirm the system's state.
Documentation: Document the expected LOADPARM and IEASYSxx members for each z/OS LPAR and compare them against IPLINFO output during audits.
Troubleshooting First Step: Make checking D IPLINFO one of the initial diagnostic steps when encountering unexpected system behavior or performance issues.
Security Awareness: Be aware that IPLINFO provides sensitive system configuration details; restrict access to operator consoles and commands to authorized personnel.