Defining and starting a coupling facility data table server region

You activate a coupling facility data table pool in an MVS™ image by starting up a coupling facility data table server region for that pool.

About this task

You can start the server as a started task, started job, or as a batch job. The job or task must invoke the coupling facility data table server region program, DFHCFMN, from an APF-authorized library. DFHCFMN is in the CICS® authorized library, CICSTS54.CICS.SDFHAUTH.

Procedure

  1. Specify the DFHCFMN program either in a SYSIN data set defined in the JCL, or in the PARM parameter on the EXEC statement.
  2. Specify the mandatory and optional startup parameters for the DFHCFMN program.
    If you specify a startup parameter in both the SYSIN data set and the PARM parameter, the PARM value overrides the SYSIN value because the MVS START command can override the PARM value.
    1. You must specify a SYSPRINT DD statement for the print file.
    2. You must specify a SYSIN DD statement for the server parameters.
    3. You must specify the TS pool name.
    4. You must concatenate the license activation data set (the SDFHLIC library) to the STEPLIB DD statement.
    5. It is recommended that you specify the REGION parameter.
      This parameter ensures that the coupling facility data table server region has enough storage to process the maximum number of data table requests that can run concurrently.
    6. It is recommended that you specify TIME=NOLIMIT.
      The server task remains in a wait during most normal processing, because server processing is performed under the TCB of the client CICS region. If you omit this parameter, your server job could fail with abend S522 (wait limit exceeded), depending on the JWT value specified in the SMFPRMxx member of SYS1.PARMLIB.
    7. Specify additional parameters as required.
      For example, you might want to control the maximum number of queues that are to be supported in the pool and the number of buffers the server is to allocate.

Results

Tip: The easiest way to ensure that all pool-related parameters are consistent across MVS images is to use the same SYSIN parameter data set, or an identical copy of it, for all servers accessing the same pool, and to specify in the PARM field any parameters that vary between servers.

Coupling facility data table server JCL example

Figure 1. Sample JCL to start a CFDT server address space
//PRODCFD1 JOB  ...
//CFSERVER EXEC PGM=DFHCFMN,REGION=40M,TIME=NOLIMIT    CICS CFDT Server
//STEPLIB  DD   DSN=CICSTS54.CICS.SDFHAUTH,DISP=SHR    Authorized library
//         DD   DSN=CICSTS54.CICS.SDFHLIC,DISP=SHR     License activation data set
//SYSPRINT DD   SYSOUT=*                               Messages and statistics
//SYSIN    DD   *
POOLNAME=PRODCFD1                                      Pool name
MAXTABLES=100                                          Allow up to 100 tables
/*