IPL

Initial Program Load

Enhanced Definition

The mainframe equivalent of booting or restarting the operating system. IPL loads the z/OS nucleus into memory and initializes the system for operation.

Key Characteristics

- System initialization process
- Nucleus loading
- Subsystem activation
- Hardware initialization
- Configuration loading
IPL Types:
- Cold Start: Complete system initialization
- Warm Start: Resume from previous state
- Quick Start: Minimal initialization
- Emergency: Recovery mode IPL
IPL Process:
1. Hardware reset 2. Load IPL text from IPLVOL 3. Initialize control blocks 4. Load nucleus modules 5. Process LOADxx and IEASYSxx parmlib members 6. Start master scheduler 7. Activate subsystems 8. Mount catalog volumes 9. System ready for work
PARMLIB Parameters:
- LOADxx: Load parameters
- IEASYSxx: System parameters
- CONSOLxx: Console definitions
- IEAIPxx: Installation exits
- PROGxx: APF and LNKLST