The task of "tuning" a system is an iterative and continuous process, and it is the discipline that most directly impacts all users of system resources in an enterprise. The z/OS® Workload Management (WLM) component is an important part of this process and includes initial tuning of selecting appropriate parameters for various system components and subsystems.

After the system is operational and criteria have been established for the selection of jobs for execution through job classes and priorities, WLM controls the distribution of available resources according to the parameters specified by the installation.

WLM, however, can deal with only available resources. If these are inadequate to meet the needs of the installation, even optimal distribution may not be the answer; other areas of the system should be examined to determine the possibility of increasing available resources. When requirements for the system increase and it becomes necessary to shift priorities or acquire additional resources (such as a larger processor, more storage, or more terminals), the system programmer needs to modify WLM parameters to reflect changed conditions.