This gap can be controlled separately for Base and Upper cabinets. The common parameter if the Face Frame Stile Thickness found in the Face Frame Common section of the Face Frame tab. On the Base Cabinets tab, in the Base General section, the parameter Door/Drawer Front Thickness is the other parameter for Base cabinets. If the Face Frame Stiles Thickness is 13/16″ and the Door/Drawer Front Thickness on the Base Cabinets tab is 3/4″ the the Base gap will be 13/16″ – 3/4″ = 1/16″. Similarly for the Upper cabinets. Here are the two equations.
Base Cabinets: Gap = Face Frame Stiles Thickness – Door/Drawer Front Thickness (on the Base Cabinets tab in Base General section)
Upper Cabinets: Gap = Face Frame Stiles Thickness – Door/Drawer Front Thickness (on the Upper Cabinets tab in Upper General section)
This is true even for Frameless designs.