Just about anything related to the OS architecture.
Yet Another Paper, for the "operating systems" class. I still have to go over and see what, if anything, IBM has about the system on their website. I'm aware it was a batch processing OS, with multithreading added in later versions of the OS. I've found some good info on the web, but I'm still lacking in specifics on how the OS itself functioned.
Nobody wins in a butter eating contest
You may want to look at Hercules.
Hercules is an open source software implementation of the mainframe System/370 and ESA/390 architectures, in addition to the new 64-bit z/Architecture. Hercules runs under Linux, Windows 98, Windows NT, Windows 2000, Windows XP, and Mac OS X 10.2 and later.
Lots of links there.
Sorry, can't help. Me being an Application Programmer then.