4.2BSD VAX: data/stack segments > 6Mb

[Dave Martindale]

Note that when growing the virtual address space, you can double DMMAX
if you like - that results in larger maximum-size blocks on the paging
device, but then you need only about half as many map entries to
handle the larger address space.  That's what I did here, and I don't
think that UPAGES needed to be grown.  Of course, all the other
comments about dependencies and recompiling user programs still apply.