We have 4 production databases running on one AIX server. There are other
applications using the AIX server as well. Consolidated server.

My Sys Admin informed that anytime, more memory is added to our AIX server,
Oracle takes about 80%. 2 Gig was added to the Box and Oracle took about 80%.
Last weekend 4 extra Gig of memory was added to the box and now Oracle seems to
take about 80%.

Can I get some explanation of what is going on?

It seems like any time more memory is added to the box, Oracle takes as much as
it needs and does not return it Or something. I don't understand what's going