Workload management
Workload management generally means effectively distributing work around a system so that it can run in the most efficient way. In the context of CICS® workload, it is the process of routing work to CICS regions so that the work can be efficiently executed. Workload management can occur before the work reaches CICS: for example, by selecting a CICS terminal-owning region (TOR) as the start point for a transaction. Or it can occur after the work arrives in CICS: for example, by selecting an appropriate region in CICS (typically, an application-owning region, or AOR) to which the transaction is routed. With CICS, there are a number of options for workload management.
What options do I have for workload management?
- CICSPlex® SM workload management (WLM)
- CICSPlex SM WLM is the CICS implementation of workload management. z/OS® Workload Manager and Sysplex Distributor are concerned with sysplex
efficiency, high availability and efficiency of TCP/IP, which typically occur before work reaches
CICS. CICSPlex SM WLM is concerned with the efficiency
of work processing after it reaches CICS. CICSPlex SM selects the most efficient region to which the
work will be sent.
If you run more than about three or four AORs, you can benefit from CICSPlex SM WLM. CICSPlex SM gives the most granular control over workload execution in CICS and, for that reason, it is the most widely-adopted workload management solution. For more information, see How it works: CICSPlex SM workload management (WLM).
- z/OS Workload Manager (WLM)
- The Workload Manager component of z/OS monitors a sysplex and determines how much resource should be given to each item of work in the sysplex to try to meet user-defined goals. For more information, see How it works: z/OS Workload Manager (WLM).
- Sysplex Distributor
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Sysplex Distributor is a component of IBM® z/OS Communications Server and provides TCP/IP load balancing across a sysplex (that is, multiple LPARs). It can be combined with TCP/IP port sharing. Sysplex distributor is a combination of the high availability features of distributed DVIPA and the workload optimization capabilities of WLM. The TCP/IP stacks can be configured to request workload information from WLM, enabling the distributing stack to forward those connections that are based on the workload of each of the target stacks. The WLM workload information is based on a comparison of available general CPU capacity for each target system. For more information, see Sysplex distributor in z/OS Communications Server: IP Configuration Guide.
- Write your own solution
- Although less commonly-used than the IBM-provided solutions, it is possible to write your own means of distributing workload. In CICS, this is done through a user-written dynamic routing program. For more information, see Writing a dynamic routing program.
Your options are not mutually-exclusive. You can use any combination of z/OS Workload Manager, Sysplex Distributor, and CICSPlex SM. For example, you might have a TCP/IP workload that uses Sysplex Distributor in a high-availability context to route incoming work into a CICS TOR. You might then use CICSPlex SM WLM to determine the most effective regions for the execution of the work. Or, you might choose to use only CICSPlex SM to control your CICS workloads.