VMS Help PASCAL, /ZERO_HEAP D=/ZERO_HEAP  *Conan The Librarian (sorry for the slow response - running on an old VAX)

                                   OpenVMS Alpha Only
  /NOZERO_HEAP

  Specifies that heap memory should be  zeroed  after  allocation.
  By  default,  the  Pascal RTL will return zero-filled memory for
  each call to the NEW builtin.  Using the /NOZERO_HEAP  qualifier
  can increase runtime performance.