Executing InfoSphere CDC for z/OS

The member named CHCPROC in the SCHCCNTL data set contains sample JCL for executing InfoSphere® CDC. This JCL is in the form of a JCL procedure. After appropriate modifications, it can be catalogued by storing it in a system procedure library, or used as the basis for producing a job that can be submitted for execution in batch mode. If the modified JCL is catalogued in a system procedure library, then it can be called by JCL that is submitted as a batch job, or referenced by a z/OS® START command entered on a system console. If it is used to produce a job for submission to batch execution, then it can be used either as an in-stream procedure within the job's JCL, or stripped down to raw step execution JCL.

Whatever the manner in which the CHCPROC sample is used, the main distinction is whether InfoSphere CDC executes as a started task or a batch job.

If InfoSphere CDC is executed as a batch job, then the JOB statement must specify the security identifier that has been assigned to the InfoSphere CDC address space, and used to replace the <CHCUserID> substitution placeholder. This security identifier is coded as the value of the USER keyword on the JOB statement. A password (the value of the PASSWORD keyword) may also be required, if the submitter of the job does not have surrogate capability for the security identifier.

If InfoSphere CDC is executed as a z/OS started task, then the appropriate steps must be taken to associate the security identifier with the z/OS started task that will execute InfoSphere CDC. These steps can differ, depending on the access control software being used by the installation.

InfoSphere CDC uses storage above the bar. As distributed, the CHCPROC sample JCL has a REGION parameter coded with a value of 0M. This causes the MEMLIMIT parameter to use the defaulted value of “NOLIMIT”. If you change the REGION parameter to anything other than 0M, then the MEMLIMIT default value will no longer be “NOLIMIT”, and requests for storage above the bar may fail. If the REGION parameter value is changed, be sure to add an explicit MEMLIMIT parameter to the JCL that permits sufficient storage above the bar to be acquired.

It is of especial importance to edit the //SYSTCPD DD statement to reference the correct TCP/IP configuration statements for your system. If this is not done correctly, InfoSphere CDC will appear to start normally but any attempt to start a subscription to a remote target will fail due to communications errors. This will be due to the fact that the correct DNS (Domain Name Server) is not being referenced, so any attempt to resolve a remote host name will fail. These communications errors are often misinterpreted as software defects in our product or TCP/IP when they are, in fact, simply the result of incorrect configuration.