CICSPlex SM-related IEASYSxx parameters

In every z/OS® image that contains a CMAS, review the MAXCAD and NSYSLX parameters in the IEASYSxx member of the SYS1.PARMLIB library that you use for z/OS initialization.

MAXCAD=nnn

CICSPlex® SM uses SCOPE=ALL data spaces and does not require any SCOPE=COMMON data spaces. Consequently, CICSPlex SM does not require you to specify MAXCAD, though you may have set this to support other products in your z/OS system. If set, MAXCAD affects the number of CMAS systems that can run on your LPAR. If you need to set MAXCAD, choose a the value to include the number of SCOPE=COMMON z/OS data spaces that are required for each LPAR.

The maximum number of CMAS systems in an LPAR 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.

Include any SCOPE=COMMON data spaces that might be in use by other products in the MAXCAD value.

The lower the MAXCAD value, the more CMASs can be run at the same time on the LPAR.

At CMAS startup, if z/OS cannot allocate the required number of SCOPE=ALL data spaces, CICSPlex SM produces message EYUXC0011E with a return code of '0000000C' and the CMAS shuts down. To reduce the chance of this happening, either lower the MAXCAD value if possible, or plan to reduce the number of CMASs on the LPAR.

Calculate the maximum number of CMASs that you can have on the LPAR at this CICS® release as follows. Be aware that other releases of CICS TS might have different requirements:
  1. Subtract the maximum number of entries in the PASN-AL (510) from the current MAXCAD value. This provides the number of PASN-AL entries that remain available for use by the Environment Services System Services (ESSS) address space to access the required data spaces. For example:
    • If MAXCAD is set to the maximum possible value of 250, and the PASN-AL limit is 510, the calculation is: 510 (PASN-AL limit) - 250 (MAXCAD value) = 260 available entries left on the PASN-AL.
  2. Divide the remaining PASN-AL entries by the number of SCOPE=ALL data spaces that each CMAS requires. This is the number of CMASs per release that can be started at the same time on the LPAR. For example, taking the number of PASN-AL entries from the previous step:
    • Each CMAS typically uses 19 SCOPE=ALL data spaces, so the calculation is: 260/19 = 13.68. The maximum number of CMASs on the LPAR is 13.
To establish the count of SCOPE=ALL data spaces that are allocated to the ESSS, issue this command from z/OS: 
/D A,EYUXnnn

EYUXnnn specifies the ESSS address space and must reflect the release of CICS TS that you are running. For example, it is EYUX640 for CICS TS beta.

The last 4 bytes of the DSPNAME contain the SYSID of each CMAS.

NSYSLX=nnn
Set or increase the value to include the minimum number of linkage indexes (LXs) that are required by CICSPlex SM. One LX is required for the Environment Services System Services (ESSS), so the minimum number of LXs required for use by CICSPlex SM is one.

For more information about this parameter, see z/OS MVS Initialization and Tuning Reference.