A method and apparatus is disclosed providing an improvement in performance for arithmetic computations by a computer system for calculations which include decimal numeric variables. The improvement in at least one embodiment includes use of a special compiler in cooperation with a special decimal numeric subroutine library. The compiler provides comparative alignment information based upon comparing alignments of a plurality of decimal variables. The decimal subroutine library can then provide improved performance at run time by utilizing the information compared by the compiler at compiler time rather than making those computations repeatedly at run time.