CICSPlex SM auxiliary storage usage

When a CMAS is initialized, a number of MVS™ data spaces are created.

CICSPlex® SM uses these data spaces to allow quick access to data from a CMAS and the MASs attached to it. Although the data spaces are logically owned by the CMAS, they are physically owned by the ESSS address space (EYUX560). The data spaces are deleted when the CMAS that logically owns the data spaces, and all local MASs, and batch jobs, that are attached to that CMAS are stopped. The data spaces are re-created when the CMAS is initialized again.

The number of data spaces created depends on the CACHEDSNUM value for the CMAS. This setting controls the number of data spaces allocated for each component, except the data cache manager, which has only one data space. Therefore, the number of SCOPE=ALL data spaces required for a CMAS can be calculated as follows:

number of SCOPE=ALL data spaces = ( 9 * CACHEDSNUM ) + 1

The default value of the CACHEDSNUM parameter is 2, and normally you do not change it unless advised to do so by IBM® Support. Therefore, each CMAS typically requires 19 SCOPE=ALL data spaces.

The size of the data spaces depends on the amount of work (such as end-user interface, workload management, MAS resource monitoring, and real-time analysis processing) that the CMAS is performing, and the number of MASs connected to the CMAS. The size ranges from 20 MB of storage in a relatively idle CICSPlex SM configuration to well over 100 MB of storage in a configuration that is complex in both the number of MASs and the amount of work requested. If you do not prepare for such an increase in storage usage, you might encounter auxiliary storage shortages when you first start to use CICSPlex SM.

To avoid such auxiliary storage shortages, ensure that your auxiliary storage can handle an increase of 100 MB of storage in the environment. Additionally, you can monitor the CICSPlex SM data space use by using an external monitor package to determine the amount of storage the EYUX560 job uses.

If you contact IBM support personnel because of auxiliary storage shortages, you might be asked to use CICSPlex SM online debugging transactions (COD0 and CODB) to evaluate the storage use of EYUX560. For information about the COD0 and CODB transactions, see Using the interactive debugging transactions (COD0 and CODB).

If auxiliary storage shortages do occur, you can alleviate the problem by either dynamically increasing your auxiliary storage capability, or causing CICSPlex SM to free the allocated data spaces:
  1. To dynamically increase auxiliary storage capacity, allocate an additional page data set, then use the MVS console command PAGEADD to make the new page data set available.
  2. To cause CICSPlex SM to free the allocated data spaces, first stop the CICSPlex SM agent in all local MASs connected to the CMAS. To stop the agent, use the COSH transaction for each MAS or, if the MAS is a WUI server, use the COVC and COSH transactions.

    If a local MAS is acting as a CICSPlex SM WLM TOR, and the DTR program is specified as EYU9XLOP for that MAS, you must change the DTR program from EYU9XLOP before you can use the COSH transaction against that MAS. For example, you can change it to the IBM default program DFHDYP.

  3. After the CICSPlex SM agent is stopped in all local MASs, stop the CMAS itself using the COSD transaction.
  4. After the auxiliary storage capability is increased, you can restart the CMAS. To reconnect any local MASs that remained active after the CICSPlex SM agent was stopped, run the COLM transaction in those CICS® regions.
You can run COLM using a modify command from the CONSOLE.