Preheat the oven to 350 degrees. Spray a 9x13 pan with non stick spray. Dump the can of pineapple juice and all in and spread out to cover the bottom of the pan evenly. Next spoon on the cherry pie filling as evenly as possible, doesnt matter though you can just glop it on however (you can use and filling though). Next sprinkle the yellow cake mix and spread out even with you hand. Cut the stick of margarine into thin pads and lay on top of the cake mix (you can also melt it on the microwave and pour it on). Put in the oven for 30-50 min or until the top is golden brown.