Writes all modified pages in an active private or global section
    back into the section file on disk. One or more I/O requests are
    queued, based on the number of pages that have been modified.

    The $UPDSECW service completes synchronously; that is, it returns
    to the caller after writing all updated pages.

    For asynchronous completion, use the Update Section File on Disk
    ($UPDSEC) service; $UPDSEC returns to the caller after queuing
    the update request, without waiting for the pages to be updated.

    In all other respects, $UPDSECW is identical to $UPDSEC. For
    additional information about the $UPDSECW service, see the
    description of $UPDSEC.

    Format

      SYS$UPDSECW  inadr [,retadr] [,acmode] [,updflg] [,efn] [,iosb]

                   [,astadr] [,astprm]

    C Prototype

      int sys$updsecw  (struct _va_range *inadr, struct _va_range

                       *retadr, unsigned int acmode, char updflg,

                       unsigned int efn, struct _iosb *iosb, void

                       (*astadr)(__unknown_params), int astprm);