VMS Help FORTRAN, Statements, Directive Statements, DO_PARALLEL  *Conan The Librarian (sorry for the slow response - running on an old VAX)

  CPAR$ DO_PARALLEL [distribution-size]

  The DO_PARALLEL compiler directive statement identifies an indexed
  DO loop that is to be executed in parallel.

  The DO_PARALLEL directive must precede the DO statement for each
  parallel DO loop.  No source code lines, other than the following
  can be placed between the DO_PARALLEL directive statement and the
  DO statement:  a CDEC$ INIT_DEP_FWD directive, a CDEC$ NOVECTOR
  directive, placeholder lines, comment lines, or blank lines.

  You can specify how the DO loop iterations are to be divided up
  among the processors executing the parallel DO loop.  For example,
  if a parallel DO loop has 100 iterations and you specify a
  distribution size of 25, iterations will be distributed to each
  processor for execution in sets of 25.  When a process completes
  one set of iterations, it then begins processing the next
  unprocessed set.  If the number that you specify for distribution
  size does not divide evenly into the number of iterations, any
  remaining iterations are run in the last process.

  The expression that you use to specify the distribution size must
  be capable of being evaluated as a positive, nonzero integer.  If
  necessary, it is converted to an integer.  For example, 5.2 is
  acceptable and is converted to 5.  The number 0.2 is not
  acceptable, however, because it is converted to 0.