That should be the "Tolerance" setting in the "Process" tab.
However, judging from your screen shot, the process had still been in the first stage (at full size steps). It will never stop there. It tries to locate the minimum at the initial step size resolution, only then starts a second scan at half that step size, and there it will stop if the value can be confirmed within the tolerance.
With LINEAR you should also always try to start (very) close to the proper focus.

Read More...