If you are running z/OS 1.2 or higher, you might choose to use the dynamic application environment. In that case, use the Administrative console to turn on the dynamic application environment. Use the Administrative console to provide the JCL proc name for the servant and the JCL Parm for the servant. Whether or not you use the dynamic application environment, you will need to follow the instructions below to set the WLM goals.
Setting the WLM goals properly can have a very significant effect on application throughput. The WebSphere for z/OS system address spaces should be given a fairly high priority. As work comes into the system, the work classification of the enclaves should be based on your business goals.
Java garbage collection runs under this classification. Java GC is a CPU and storage intensive process, so if you set the velocity goal too high GC could consume more of the system resources than desired. On the other hand, if your Java heap is correctly tuned, GC for each server region should run no more than 5% of the time. Also, providing proper priority to GC processing is necessary since other work in the server region is stopped during much of the time GC is running.
JSP compiles run under this classification. If your system is configured to do these compiles at runtime, setting the velocity goal too low could result in longer delays waiting for JSP compiles to complete.
Application work is actually classified under the work manager.
It is usually a good idea to make the goals achievable. For example, a goal that 80% of the work will complete in .25 seconds is a typical goal. Velocity goals for application work are not meaningful and should be avoided.
Your goals can be multi-period. This might be useful if you have distinctly short and long running transactions in the same service class. On the other hand, it is usually better to filter this work into a different service class if you can. Being in a different service class will place the work in a different servant which allows WLM much more latitude in managing the goals.
Example:
Application-Environment Notes Options Help -------------------------------------------------------------------------- Modify an Application Environment Command ===> ______________________________________________________________ Application Environment Name . : BBOASR2 Description . . . . . . . . . . WAS.V40.WB02 Application server Subsystem Type . . . . . . . . . CB Procedure Name . . . . . . . . . BBOASR2S Start Parameters . . . . . . . . IWMSSNM=&IWMSSNM __________________________________________ __________________________________________ Limit on starting server address spaces for a subsystem instance: 1 1. No limit 2. Single address space per system 3. Single address space per sysplex
Note: When the WLM configuration is set to no limit, you can control the maximum and minimum number of servants by specifying the product variables wlm_maximumSRCount=x and wlm_minimumSRCount=y. To specify these variables, click Severs > Application servers and go the application server page. Caution: If you specify wlm_maximumSRCount you must ensure that you specify a wlm_maximumSRCount value that is greater than or equal to the number of service classes you have defined for this application environment. Failure to do so can result in timeouts due to an insufficient number of server regions.