Writing execs that run in Non-TSO/E address spaces

As described above, you can run REXX execs in any MVS™ address space (both TSO/E and non-TSO/E). Execs that run in TSO/E can use several TSO/E external functions, commands, and programming services that are not available to execs that run in a non-TSO/E address space. Writing execs that run in the TSO/E address space describes writing execs for TSO/E.

If you write a REXX exec that will run in a non-TSO/E address space, you can use the following in the exec:

All keyword instructions that are described in Keyword instructions
All built-in functions that are described in Functions.
The TSO/E external functions SETLANG and STORAGE. See TSO/E external functions for more information.
The following TSO/E REXX commands:
- MAKEBUF - to create a buffer on the data stack
- DROPBUF - to drop (discard) a buffer that was previously created on the data stack with the MAKEBUF command
- NEWSTACK - to create a new data stack and effectively isolate the current data stack that the exec is using
- DELSTACK - to delete the most current data stack that was created with the NEWSTACK command
- QBUF - to query how many buffers are currently on the active data stack
- QELEM - to query how many elements are on the data stack above the most recently created buffer
- QSTACK - to query the number of data stacks that are currently in existence
- EXECIO - to read data from and write data to data sets. Using EXECIO, you can read data from and write data to the data stack or stem variables.
- TS (Trace Start) - to start tracing REXX execs. Tracing lets you control exec processing and debug problems.
- TE (Trace End) - to end tracing of REXX execs
- SUBCOM - to determine whether a particular host command environment is available for the processing of host commands.
The commands are described in TSO/E REXX commands.
Invoking an exec
You can invoke another REXX exec from an exec using the following instructions (the examples assume that the current host command environment is MVS):
```
"execname p1 p2 ..."

"EX execname p1 p2 ..."

"EXEC execname p1 p2 ..."
```
See Commands to external environments about using host commands in a REXX exec.
Linking to and attaching programs
You can use the LINK, LINKMVS, and LINKPGM host command environments to link to unauthorized programs. For example:
```
ADDRESS LINK "program p1 p2 ..."
```
You can use the ATTACH, ATTCHMVS, and ATTCHPGM host command environments to attach unauthorized programs. For example:
```
ADDRESS ATTACH "program p1 p2 ..."
```
For more information about linking to and attaching programs, see Host command environments for linking to and attaching programs.
TSO/E REXX programming services.
In any address space, you can use the REXX programming services, such as IRXEXEC and IRXJCL, IRXEXCOM, and IRXIC. The services are described in TSO/E REXX programming services.