VMS Help MACRO, /MIGRATION, Compiler Directives, .PRESERVE, Parameters  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 argument-list

    One or more of the symbolic arguments listed in the following
    table:

    Option         Description

    GRANULARITY    Preserves the rules of VAX granularity of writes.
                   Specifying .PRESERVE GRANULARITY causes the
                   compiler to use Alpha Load-locked and Store-
                   conditional instruction sequences in code it
                   generates for VAX instructions that perform byte,
                   word, or unaligned longword writes.
    ATOMICITY      Preserves atomicity of VAX modify operations.
                   Specifying .PRESERVE ATOMICITY causes the
                   compiler to use Load-locked and Store-conditional
                   instruction sequences in code it generates for
                   instructions with modify operands.