CA-IDMS will have to be configured to run in a non-user KEY - that is, one in the range 1 to 7. CA recommends using 4.
To accomplish this, you must take the following three steps.
1. STEPLIB must be authorized and must contain RHDCTCKR, RHDCCKUR, RHDCOMVS and any other aliases if they are used for RHDCOMVS in the EXEC= statement in your startup JCL (e.g. IDMSDC).
The easiest way to achieve this is to include only the IDMS software library (that which is provided as CAGJLOAD at installation) in STEPLIB and authorizing it.
It is also possible to create a separate library with only those modules in it (IDMS loads everything else from CDMSLIB), but that just provides an administrative overhead.
2. Create a PPT entry in the appropriate SYS1.PARMLIB(SCHED..) member for your startup module identifying the key.
PPT PGMNAME(RHDCOMVS) ,KEY(4),NOSWAP
3. Specify STEP=Y on the EXEC= statement in your startup JCL.
//IDMS EXEC PGM=RHDCOMVS,REGION=0M,TIME=1440,PARM='STEP=Y'
You may also want to re-create your SVC with CVKEY=4 in #SVCOPT instead of CVKEY=*, but this is not necessary if your SVC was created with #SVCOPT parameter CVKEY=* ..
If your SVC has been created with an #SVCOPT with CVKEY=n where n is a number, then the SVC will check that the CV is running in that particular key, and if it isn't, the CV will abend with an SEnn abend code where nn is the number of the SVC in hexadecimal.
If your SVC has been created with CVKEY=*, no such check is performed.
Changing your SVC would only be necessary if it had already been created with CVKEY=n where n is a number other than the one which you specified in the PPT entry.