When you want to use a newly created REXX tool just by using the TSO command. Then you need to have this REXX tool be present in a PDS which is part of DD SYSEXEC or SYSPROC (Type TSO ISRDDN, and go few pages down to see these DD names and the PDS system allocates to them).
Sometimes your organization will have a common PDS under these DD names (SYSEXEC or SYSPROC) to which you can move your new REXX tool exec and start using it.
In case you do not have one common PDS, or you do not have authority to add the new REXX exec member to that PDS, you can add your own PDS to either of the DD names (SYSEXEC or SYSPROC).
The below attached REXX – INITIAL SETUP tool will add the PDS (where your REXX execs) reside to the DD SYSEXEC (in TSP ISRDDN).
Once you have added your PDS, you can just execute any REXX toll by TSO command. For example, your tool name is MYTOOL. To execute the tool from any screen, simply type “TSO MYTOOL”.
Please note if you have added your REXX PDS by this method, the next time you login, system automatically resets the PDS (under SYSEXEC, SYSPROC) and you will not see your REXX PDS. So you need to run this initial setup tool again. You can also ask your SYSTEM PROGRAMMER to add your PDS permanently to SYSEXEC or SYSPROC, so you need not do this.
Please share if this is useful to you.