In the TSO/E address space, a default language processor environment is automatically initialized when a user logs on and starts a TSO/E session. The IRXINIT initialization routine initializes language processor environments. When a user invokes ISPF, another language processor environment is initialized. The language processor environment initialized for ISPF is a separate environment from the one that is initialized when the TSO/E session is started. Similarly, if you enter split screen mode in ISPF, another language processor environment is initialized for the second ISPF screen. Therefore, at this point, three separate language processor environments exist. If the user invokes an exec from the second ISPF screen, the exec executes within the language processor environment that was initialized for that second screen. If the user invokes an exec from TSO/E READY mode, the exec executes within the environment that was initialized when the user first logged on.

When the user returns to a single ISPF screen, the language processor environment associated with the second ISPF screen terminates automatically. The IRXTERM termination routine terminates the language processor environment. Similarly, when the user exits from ISPF and returns to TSO/E READY mode, the environment associated with the ISPF screen is terminated. When the user logs off from TSO/E, that language processor environment is then terminated.