Line bottom of 9 x 12-inch pan with mixture of 1 stick margarine and 24 crushed graham crackers. Bake at 375 degrees for 8 to 10 minutes. Whip 2 sticks margarine, powdered sugar and vanilla; spread over graham cracker crust. Cut bananas, lengthwise; place over whipped mixture. Cover bananas with pineapple; cover all with Cool Whip. Chill overnight.