Library /sys$common/syshlp/ncphelp.hlb SET, LINE, SERVICE TIMER milliseconds  *Conan The Librarian (sorry for the slow response - running on an old VAX)

 Does not apply to X.25 lines.  Specifies the maximum amount of time
 allowed to elapse before a receive request completes while performing
 service operations on a line.  Milliseconds must be a decimal integer
 from 1 to 65,535.  The default value is 4000 (4 seconds).