How to choose a fixed address for shared memory mapping

I would like to use shared memory between several processes, and would like to be able to keep using raw pointers (and stl containers).

For this purpose, I am using shared memory mapped at a fixed address:

segment = new boost::interprocess::managed_shared_memory(
    boost::interprocess::open_or_create,
    "MySegmentName",
    1048576, // alloc size
    (void *)0x400000000LL // fixed address
);

What is a good strategy for choosing this fixed address? For example, should I just use a pretty high number to reduce the chance that I run out of heap space?