TSO/E environment initialization

The TSO/E environment is initialized to indicate that SYSTSIN is the current input source and SYSTSPRT is the current output source. The TSO/E Environment Service uses existing allocations for the SYSTSIN and SYSTSPRT files if you have allocated them. Otherwise, it allocates them as DUMMY data sets. You must allocate SYSTSPRT and SYSTSIN correctly and ensure that they are closed upon entry to IKJTSOEV. During initialization, the TSO/E Environment Service opens SYSTSIN and SYSTSPRT, but it does not read from the SYSTSIN file or process any command input.

Note:

The TSO/E Environment Service associates the TSO/E environment with the highest jobstep task in the calling program's address space.
The TSO/E Environment Service establishes a REXX Language Processor Environment that is associated with the task from which you invoked IKJTSOEV.
Any jobstep tasks that your application creates must use the same jobstep control block (JSCB). If your program attaches a new jobstep task with a different JSCB after the TSO/E environment is created, the new task cannot invoke TSO/E services.
You may specify a user ID through the USER parameter of the JCL that you use to start your application. In your application, the user ID is available in the PSCBUSER field in the PSCB.
The TCB key (TCBPKF) of the task under which the caller of the TSO/E Environment Service runs must match the TCB key of the highest non-system jobstep task in the address space. If the keys do not match, return code 40 (decimal) is returned, along with an indication of the mismatched keys in register 0.