From Daniel Nashed:
Domino 7.0.2+ supports Windows 2003 64bit and can leverage more than 2 GB memory for local + shared memory.
What is still not widely known among ISVs is that you need to link your applications in Visual Studio with a new flag called /LARGEADDRESSAWARE. The flag allows a program to use more than 2 GB of memory (shared + local). Without this flag an application crashes when the 2 GB memory limit is reached. The Notes API samples up to 8.5 don't use this flag and they should.