There's an emulator called Hercules[1] that lets you run (some) mainframe stuff on a PC. There are limits to what you can run on it though, mostly due to licensing issues with IBM.
You can also look at the IBM Redbooks site[2]. Search for terms like Z/OS, MVS, CICS, DB/2, etc. and you'll find a lot of IBM books, whitepapers (well, they call them redpapers, but whatever) and so on.