Preheat the oven to 350 degrees F (175 degrees C). Grease and flour three 8-inch round pans.

Cream margarine in a large bowl until smooth. Blend in eggs. Add cake mix and pineapple with juice; mix until smooth. Stir in pecans. Pour batter into the prepared pans.

Bake in the preheated oven until a toothpick inserted into the center comes out clean, 20 to 30 minutes. Cool cakes in pans on wire racks for 5 minutes. Run a table knife around the edges to loosen. Invert carefully onto cooling racks. Let cool completely, about 1 hour.

To make frosting: Beat margarine and cream cheese in a medium bowl until smooth. Gradually blend in the confectioners' sugar. Mix in pecans.

Spread frosting onto the cooled cake layers. Stack layers; frost top and sides.