The exit can provide JCL statements to the logon processor in the JCL parameter. The JCL defines terminal job resources. The logon processor uses this JCL instead of the JOB and EXEC statements that it constructs. The default JCL parameter is a maximum of 800 bytes in length, in which the exit can return a maximum of ten JCL statements. To return more than ten JCL statements, the exit can provide its own parameter for JCL. Logon processing will accept a JCL parameter containing up to 409 JCL statements, but your installation's JES capability determines the actual number of JCL statements allowed. Logon processing does not check that number. To provide your own parameter for JCL, replace the JCL parameter address supplied by LOGON with the address of the alternative parameter. Then set the current length to the number of JCL statements multiplied by 80.

The logon processor expects that each 80 bytes of the parameter contains a full 80-byte JCL statement in standard format. It uses the current length field of the parameter to determine the number of statements that the exit is returning (current length/80 = n statements).

If the exit provides JCL, it must also set the JCL bit on.

If you issue the GETMAIN macro to obtain storage for an alternative JCL parameter, you must use a job-oriented subpool (such as subpools 0 to 127) whose storage will be automatically freed when the logon job ends, or you can use the user word to save the address so that logoff exit IKJEFLD2 can access it and issue the FREEMAIN macro to free storage in the subpool.