If you do anything that effects these stats to make them go up (or down), and the stats are full, it should just set the stat to the new higher (or lower) number, instead of you needing to 'recover' to it, or having a surplus of health/stam/stun over your current cap.
I don't support having proportional increases to current totals if you are injured or fatigued, because that involves more math than just checking if the stat's current max and status are the same before doing a yes or no on a recalc.