Been a few years since I've used Mitz, but I remember seeing this every time I would make an online edit. I think it is memory allocated for online edits. I seem to remember there was somewhere where you could increase this number from 500 to a higher value. I also remember that as I would make more and more edits, the available "steps" would decrease, and I think when they got to zero, it would just ask if I wanted to increase it and I would say yes and carry on.
So basically it was never a problem as far as I could remember and never stopped me from doing what I had to do. I'm sure someone here will chime in with a more in-depth answer.