By stall I am referring to a fully developed stall, IE full departure.. Aren't you referring to prestall sink?
I have always believed that apart from stability, the canards were there to ensure the prevention of a fully developed stall. This would be achieved by having the angle of incidence of the canard set higher than the main planes, therefore ensuring the canards enter prestall sink and allowing the nose to drop before the main planes stall.
I stand to be corrected on the above of course.