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

    PQL_DBYTLM sets the default buffered I/O byte count limit for the
    amount of buffered space available to a process created by the
    Create Process ($CREPRC) system service or the DCL command RUN
    (Process).

    PQL_DBYTLM has the DYNAMIC and GEN attributes.