Actually, that's very popular myth. Dietary calcium actually tends to decrease the risk of kidney stone [Note that i am talking about dietary calcium not urinary]. Oxalates are main risk factors. calcium needs to bind with oxalates in the stomach. If this does not happen, more free oxalates are secreted as wasted produced in the urine which increase the chances of stone formation.
So, milk products are actually recommended to decrease the risk of stones.