hi Mike,

 MB> I don't see any reason why a Rexx-callable DLL could not be
 MB> multithreaded, especially since there will be only two threads and
 MB> the second one will never interact directly with the Rexx program. 
 MB> If you know of any extensions which already do this, please tell
 MB> about them.  I plan to write the DLL.

David Boll's freeware RXU (formerly known as YdbaUtil) does (amonst many
other things) multi-threading.  ftp a copy of RXU19.ZIP off hobbes
(/incoming unless they've finaly begun to clean it up).  This is his About:


 RXU is a package of diverse OS/2 Rexx External Functions. Almost all the
functions in this package are in use in many of my own programs and are 
 fairly well de-bugged.  Please let me know of any problems you encounter
in using the functions, or of any suggestions for enhancements to existing 
 functions, or ideas for new ones. 

 I've written the functions in RXU both to more fully enable Rexx as a
programming language for the OS/2 environment, and as a personal technical 
 challenge.  Since I'm not making any money off them, I do from time to
time put support/enhancement on the back burner due to other distractions. 

 I'm waiting to see what the Rexx landscape will look like in the Win95
world before I explore porting RXU (at least, the portable parts) from OS/2
to 
 Win95.   


   With the functions in the RXU function package, you can make
   use of some of OS/2's most powerful facilities, such as multi-threading,
   processes, sessions, semaphores, memory access, OS/2 queues, etc.
   Some of these features are not only useful in pure Rexx applications,
   but they allow you to write Rexx programs which can talk to compiled
   programs on their level (i.e. reference memory by address, use
   semaphores, etc.).

   Another benefit is the ability to quickly prototype real OS/2 programs
   using real OS/2 APIs so that you can cheaply 'prove' techniques
   before committing them to 'C' code.

   The capabilities provided to Rexx programs by this package, in
   conjunction with those provided by other Rexx function packages
   (database access, APPC, etc.) and the base language itself allow
   you to prototype or build Rexx applications with much of the
   functional sophistication (and complexity, unfortunately) of "real"
   OS/2 applications.

   In addition to the many OS/2 API "passthrough" functions, there are
   many Rexx-specific enhancements and additions.


   Author:        Dave Boll
                  (CompuServe = 74170,2016)
                  Internet: 74170.2016{at}compuserve.com
   Release Date:  1 November, 1995
   Version:       1.9


regards,
         hugo