Digital BW, The Print

William, 

You are generally correct, but mistaken as it applies to Photoshop.
Within PS7's memory allocation preference panel in OSX you can specify
what percentage of system memory to allow photoshop to _synamically
allocate_ to itself. This is a very very important setting - without
it photoshop might dynamically allocate nearly all of system ram to
itself if you were working on huge files, throttling the performance
of other items in your system. 

My advice, rather than looking through manuals for programs other than
PS - check out the program we're actually talking about :)