Since Endevor stores the listings in a compressed format, you will need to use Endevor or an Endevor utility to browse the listings. Depending on what you are trying to accomplish, there are several possibilities including the Endevor batch interface (C1BM3000) and the Endevor Application Programming Interface (API).
You can use the Endevor batch interface to print an Endevor listing using syntax similar to the following:
PRINT MEMBER 'XXXXXXXX' FROM DSNAME 'XXXXXXXX.LISTING'
With this method, your Rexx program could allocate all the required files, build the control statement, and then execute the Endevor batch interface to write the Endevor listing to a temporary dataset which you could then browse. On the downside, you may not be able to use this approach if you plan to execute your Rexx program while your user is already in Endevor because you will not be able to properly allocate all of the required Endevor datasets.
Another more elegant solution which you could execute from outside of Endevor and also from inside of Endevor is the Endevor Application Programming Interface. The Endevor API includes support for the PRINT MEMBER action. The Endevor API does not directly support Rexx so you would need to write a COBOL, PL1, or Assembler program to accept the parameters from your Rexx program and then call the Endevor API. Then your Rexx program could browse the output dataset from your API program.
The Endevor batch interface and the Endevor API are both documented pretty well in the Endevor documentation set and the Endevor installation libraries include some examples of each.