re-position window's bottom to screen's bottom?

I've made actions to re-position a window the left, right, or top of the screen. I can't seem to figure out a combination of the Configure Move/Resize options to make a window move to the bottom of the screen. I'd like the action to make the bottom of the active window--regardless of size--match up exactly with the bottom of the screen. Does someone have a recipe they can share?