/OPTIMIZE[=(option[,...])]
       /NOOPTIMIZE

    Enables or disables optimization options. All options are enabled
    by default except VAXREGS.

    The options are:

    Option         Description

    [NO]PEEPHOLE   Peephole optimization
    [NO]SCHEDULE   Code scheduling
    [NO]ADDRESSES  Common base address loading
    [NO]REFERENCES Common data referencing
    [NO]VAXREGS    OpenVMS Alpha systems only: Allow the use of VAX
                   registers (R0 through R12) as temporary registers
                   when they appear to be unused
    ALL            All optimizations
    NONE           No optimizations

    Note that, on OpenVMS Alpha systems, /OPTIMIZE=ALL turns on
    VAXREGS, which may generate incorrect code unless all register
    usage of all routines in the module have been correctly declared.