VMS Help Sys Parameters, PQL_DBIOLM  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    PQL_DBIOLM sets the default buffered I/O count limit for the
    number of outstanding buffered I/O operations permitted to a
    process created by the Create Process ($CREPRC) system service or
    the DCL command RUN (Process).

    PQL_DBIOLM has the DYNAMIC and GEN attributes.