Sugar Cookie Bars

1 cup butter, softened
2 cups sugar
4 eggs, beaten
2 tsp. vanilla 
5 cups flour
1 tsp. salt
1/2 tsp. baking soda

Cream butter and sugar until fluffy.  Add eggs, mixing well, then vanilla.  Add dry ingredients.  Spread on a greased jellyroll pan (13x18).  Bake at 375 degrees for 10-15 minutes, until light golden brown.  Cool completely and frost.