This unit presents what occurs during the initialization of the base control program of z/OS. It also discusses what control the system programmer has over customization of the Initial Program Load (IPL) process and what control the operator has over the IPL process.

z/OS BCP provides task management and supervisor services in order to enable the sharing of system resources and maximize the work that is processed in a given time. A solid understanding of these services is necessary to perform many system programmer activities. Examples include identifying bottlenecks, and determining status when a wait state or failure occurs.

z/OS and IBM z System provide the architectural foundation that allows greater flexibility and more design options in the development of application programs with needs that extend beyond the boundaries of a single address space.This unit examines the hardware and software facilities that enable a program to interact with other programs executing in other address spaces and use data in data spaces.

One of the primary functions of any computing system is the processing of data. Much of the data that is processed exists external to processor storage; that is, it might be out on a tape or DASD volume or it might be entered from a terminal. The handling of data requires the services of both software and hardware (channel subsystem and the devices attached to it).Understanding the roles of software and hardware in handling I/O requests is necessary for determining how to configure the hardware, how to tune the I/O configuration, and in analyzing I/O-related problems.

One of the major resources available to the users of an z/OS system is storage. Programs executing in the system, whether user applications or z/OS system routines, are vying for storage. Each of the areas of storage, however, is a limited resource, and use and availability must be managed to maintain program integrity. This managing of storage in z/OS is handled by three storage managers, virtual, real, and auxiliary. In this unit, we will gain an understanding to how each of the areas of storage is assigned, used, and managed is necessary for determining how much storage is required for your installation. This is also required for tuning your system to make the most efficient use of storage, and for analyzing storage-related failures.

The resolution of errors often requires the analysis of information produced at the time of the failure. The responsibility of the recovery termination manager (RTM) is to gather the failure indications, interface with system and application error recovery routines, and to generate the failure documentation. Understanding the function of the recovery termination manager and recovery routines is helpful for analyzing the failure documentation and for determining how to tune the system for the control of the documentation produced.