Holding Water And Big Fish

I watched Kelly Gaullop's streamer fishing video and it got me thinking about predatory fish in still water. I have always had success in the mornings and evenings when fish are generally feeding. I tend to key on fish in the shallows more in the evening time than I do in the morning. If I remember right though, most of my big fish (25 and over) have been hooked during non-feeding times. These fish were not feeding. According to the theory, they were attacking something that was in their area and they were not feeding off of it.
So what is "holding water" in a lake? Where do big fish go when they are not feeding. I believe they hold in slightly deeper water than feeding water. I also think that this water is relatively close to feeding water (shallows). I think that they mostly sit near structure (drop-offs) so that they can be safe and rest in an optimum water temperature. This allows them to move in and out of feeding water without using much energy because the feeding water is close by.

Link:http://flyfisherman.com/ftb/kgtrigger/