The Stock To Leave is the amount of stock you require left on the chained geometry after the cutting passes have been done.
Pocket, Contour, Rest Material
Enter the amount of stock to leave on the sides of pockets and contours for the On Sides parameter.
Enter the amount of stock to leave at the bottom of pockets and contours for the In Z parameter.
The amount of material that is removed will be the difference between the Amount To Remove and the Stock To Leave parameters.
If the amount is negative, SURFCAM over cuts the contour on the sides or over cuts the contour on the bottom.