Pour water over oatmeal and margarine. Let stand 20 minutes. Mix eggs and sugars. Mix dry ingredients and add to eggs. Beat well and add oatmeal. Spread onto greased and floured 10 x 15-inch jelly roll pan and bake for 20 minutes at 350 degrees. Cool and frost. Frosting: Bring to a boil the sugar and oleo; add all ingredients except powdered sugar and vanilla. Boil for 3 minutes, stirring constantly. Remove from heat and add vanilla. When nearly cool, add powdered sugar and beat well. Spread on cooled bars. Bars are best when made a day before needed and frosting sets up better.