Library /sys$common/syshlp/uafhelp.hlb MODIFY, Qualifiers, /BYTLM  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /BYTLM=value

    Specifies the buffered I/O byte limit for the BYTLM field of the
    UAF record. The buffered I/O byte limit is the maximum number
    of bytes of nonpaged system dynamic memory that a user's job
    can consume at one time. Nonpaged dynamic memory is used for
    operations such as I/O buffering, mailboxes, and file-access
    windows. The default is 32768 on VAX systems and 64000 on Alpha
    systems.