DSXchange

Anybody here have any links to or thoughts on memory usage by Datastage PX? The problem is this. We are seeing behaivor that indicates that the server is running out of memory from a datastage and os side but it isn't quite showing up on our performance tools. It seems to me that I remember that the PX stuff somehow starts rolling stuff out to scratch disk if it runs out of memory. Does PX somehow know how much memory is available to it. Does it then under the covers manage that memory by doing it's own swapping out to the scratch disks? Any thoughts or help appreciated.
ART