Heads up: deepest stack at which push/fold from button is +ev

[prinsrob]

Hi,

Suppose my opponent knows my strategy and plays optimal against it. My stratey is to only play the button and only push or fold hands (heads up, no limit hold'em).

What is the deepest stack at which the optimal button strategy (with the given constraint of only pushing and folding) is +ev? And how much is this ev per hand for, say, a 10bb stack (I suppose this is +ev for a 10bb stack, not sure though).

[I posted this in Poker Theory but got no response there.]