VMS Help SET, HOST, /DTE, Qualifiers, /MAX_BUFFERS  *Conan The Librarian (sorry for the slow response - running on an old VAX)

       /MAX_BUFFERS=number-buffers

    Specifies the maximum number of receive buffers. Receive buffers
    are buffers used to receive incoming data from the modem port.
    They are allocated as they are required.

    By default, the maximum number of receive buffers is 100. The
    minimum number you can specify is 20.