Library /sys$common/syshlp/nclhelp.hlb set, x25_protocol, dte, pvc, window_size  *Conan The Librarian (sorry for the slow response - running on an old VAX)

    Default: No default    Value: 1-127

    Window size for the PVC. The value of this characteristic derives
    from an argument to the create command.

    Example:

    set x25 protocol dte dte-1 pvc PVC-1 window size 2