Declares the entry point of a JSB routine to the compiler. This
    directive does not preserve any VAX register values (R2 through
    R12) unless the PRESERVE parameter is specified. The routine
    itself may save and restore registers by pushing them on the
    stack, but this will not preserve the upper 32 bits of the
    registers. See also .JSB_ENTRY.

                                 WARNING

       The .JSB32_ENTRY directive can be a great time-saver if you
       are sure that you can use it. If you use .JSB32_ENTRY in a
       situation where the upper 32 bits of a register are being
       used, it may cause very obscure and difficult-to-track bugs
       by corrupting a 64-bit value that may be several calling
       levels above the offending routine.

       .JSB32_ENTRY should never be used in an AST routine,
       condition handler, or any other code that can be executed
       asynchronously.

    Format

      .JSB32_ENTRY  [input] [,output] [,scratch] [,preserve]