There is a performance penalty. I have measured it for aligned and unaligned signed halfword, i.e., signed binary fixed(15,0), in compiled PL/I code and found that it is usually about 13%, which may be trivial or important depending upon context.
More important in multiple-CP environments, I think, is that there are contexts in which alignment|non-alignment determines whether an operation is performed as an interlocked|non-interlocked update. See the discussion of the ASI and AGSI instructions on page 7-25 of the current PrOp. John Gilmore, Ashland, MA 01721 - USA ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
