System Generation

An operational system is a combination of the z/TPF system, application programs, and people. People assign purpose to the system and use the system. The making of an operational system depends on three interrelated concepts:

• System definition: The necessary application and z/TPF system knowledge required to select the hardware configuration and related values used by thez/TPF system software.
• System initialization: The process of creating the z/TPF system tables and configuration-dependent system software.
• System restart and switchover: The procedures used by the z/TPF system software to ready the configuration for online use.

The first two items are sometimes collectively called system generation; also installing and implementing. System definition is sometimes called design. System restart is the component that uses the results of a system generation to place the system in a condition to process real-time input. The initial startup is a special case of restart and for this reason system restart is sometimes called initial program load, or IPL. System restart uses values found in tables set up during system generation and changed during the online execution of the system. A switchover implies shifting the processing load to a different central processing complex (CPC), and requires some additional procedures on the part of a system operator. A restart or switchover may be necessary either for a detected hardware failure, detected software failure, or operator option. In any event, system definition (design), initialization, restart, and switchover are related to error recovery. This provides the necessary background to use this information, which is the principal reference to be used to install the z/TPF system.