Comment by JdeBP

I might have an OS/2 programming manual. But I don't need it. (-: This was not an OS/2 thing. We had to make map data structures using thread IDs. Or our language runtimes did.

Look to Windows NT rather than to OS/2 for thread-local storage. TlsAlloc() et al. were in the Win32 API right from NT 3.1, I think.