Hi Lucas,
I think this topic has been raised several times earlier.
Like in the below thread.
https://scn.sap.com/thread/3424524
As you are aware OS tools will monitor from a operating system perspective which would be the resident memory. There is no mechanism as such to reduce the resident memory usage like the high water mark in DB6 
.
System is would be monitored by the DBA team and the operating system administrators team. They wouldnt understand that the used memory is low but the resident memory is high.
So is there a mechanism to reduce the resident memory usage or bring down especially in cases when there is a large gap.