z/OS System Services Structure

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.