OS/2 API Trace allows you to trace the 16-bit and 32-bit OS/2 APIs used by any application running on any 32-bit version of OS/2 (2.0 or later) without requiring the application's source code or requiring the application to be recompiled/relinked. Simply enable the application for tracing and run it, and the OS/2 API calls (and optionally their parameters) made by the application are logged to a text file that is already formatted and in English. Tracing can also be customized, controlled, and summarized.
Hobbes: http://hobbes.nmsu.edu/h-search.php?sh=1&button=Search&key=os2trace.zip
You can read more about OS/2 API Trace at Dave Blaschke web site: