The type of language processor environment that IRXINIT initializes depends on the address space in which IRXINIT creates the environment. Whether a language processor environment is integrated into TSO/E is determined by the setting of the TSOFL flag (see Flags and corresponding masks). The TSOFL flag is one characteristic (parameter) that IRXINIT uses to initialize a new environment. If the TSOFL flag is off, the new environment is not integrated into TSO/E. If the flag is on, the environment is integrated into TSO/E.

In non-TSO/E address spaces, language processor environments cannot be integrated into TSO/E. Therefore, when the system automatically initializes an environment in a non-TSO/E address space, the TSOFL flag is off. Similarly, if you explicitly invoke the initialization routine (IRXINIT) to initialize an environment in a non-TSO/E address space, the TSOFL flag must be off.

In the TSO/E address space, a language processor environment may or may not be integrated into TSO/E; that is, the TSOFL flag can be on or off. When the system automatically initializes an environment in the TSO/E address space, the environment is integrated into TSO/E (the TSOFL flag is on). If you explicitly invoke the initialization routine, IRXINIT, to initialize an environment in the TSO/E address space, the environment may or may not be integrated into TSO/E. That is, the TSOFL flag can be on or off. You may want to initialize an environment in the TSO/E address space that is not integrated into TSO/E. This lets you initialize an environment that is the same as an environment for a non-TSO/E address space. By doing this, for example, you can test REXX execs you have written for a non-TSO/E address space.

The following topics describe the two aspects of REXX processing.

Functions, Commands, and Services in an Exec: The type of language processor environment in which a REXX exec runs affects the kinds of functions, commands, and services you can use in the exec itself. If the exec runs in an environment that is integrated into TSO/E, you can use TSO/E commands, such as ALLOCATE, TEST, and PRINTDS in the exec. You can also use TSO/E programming services, such as the parse service routine (IKJPARS) and the dynamic allocation interface routine (DAIR). The TSO/E programming service routines are described in z/OS TSO/E Programming Services. In addition, the exec can use all the TSO/E external functions, ISPF services, and can invoke and be invoked by CLISTs.

If an exec runs in an environment that is not integrated into TSO/E, the exec cannot contain TSO/E commands or the TSO/E service routines, such as IKJPARS and DAIR, or use ISPF services or CLISTs. The exec can use the TSO/E external functions SETLANG and STORAGE only. The exec cannot use the other TSO/E external functions, such as MSG and OUTTRAP. Using REXX in different address spaces describes the instructions, functions, commands, and services you can use in REXX execs that you write for TSO/E and for non-TSO/E address spaces.

Different Characteristics for the Environment: When IRXINIT initializes a language processor environment, IRXINIT defines different characteristics for the environment. The three parameters modules TSO/E provides (IRXTSPRM, IRXISPRM, and IRXPARMS) define the default values for initializing environments. If you provide your own parameters module or explicitly invoke the initialization routine (IRXINIT), the characteristics you can define for the environment depend on the type of environment.

Some characteristics can be used for any type of language processor environment. In some cases, the values you specify may differ depending on the environment. Other characteristics can be specified only for environments that are integrated into TSO/E or for environments that are not integrated into TSO/E. For example, you can provide your own replaceable routines only for environments that are not integrated into TSO/E. TSO/E also provides exit routines for REXX processing. In general, you can provide exits for any type of language processor environment (integrated and not integrated into TSO/E). One exception is the attention handling exit, which is only for environments that are integrated into TSO/E. Replaceable routines and exits describes the replaceable routines and exits in more detail.

Specifying values for different environments describes the environment characteristics you can specify for language processor environments that either are or are not integrated into TSO/E.