Should StateServer (aspnet_state.exe) release RAM when a session ends?

I am noticing that the StateServer service only grows in memory usage.

When a user logs out the session is ended with:

Session.Clear()
Session.RemoveAll()
Session.Abandon()

I assumed that StateServer would then release some memory, but it will actually consume a bit more.

In web.config I hav开发者_开发百科e the timeout set to 20 minutes. The sessions do time out after 20 minutes of no activity, but StateServer doesn't release any memory when they do.

Is this normal behavior?