Propane Valve under 320 CS-S

It is connected to a switch on one of the struts for the rear hatch.  It turns off the gas flow to the stove when the hatch is closed

A common modification is to add an additional switch in series in that circuit to turn the gas valve off when the stove is not being used. 
The solenoid valve draws ~1 amp constantly while the hatch is open.  When camping off grid, this is a significant draw especially if you keep the hatch open as part of living space.