There was a lot of banking software written in DB2 for OS/2 back in the early nineties. OS/2 wouldn't die because a lot of banks didn't want to replace all of their accounting infrastructure just because IBM got it's ass kicked by Microsoft on the desktop.
OS/2 was a pretty cool product, and compared to Windows 3.1 it was a vast improvement. Windows 95 killed it on the PC, but OS/2 Warp Server carried on for some time to support all of those database applications still in use by legacy customers.
Hopefully the link above can provide you with a bit more history and information about current support efforts.