Does boost library have a pseudo infinity value?

I am using the boost library to solve a max flow problem, however some of my edges have unrestricted capacities and i was wondering if the boost library had an in built "infinity" value, in the same way that cplex or something like that does. Currently I am using an arbitrarily large value for the capacity so that the edges never get saturated, however this is a bit of a "hackish" solution, and may give me some problems further down the track as the values of the other capacities may change (sometimes by wildly different values) so i don't want to have to re-calculate my upper bound every time anything changes. If there was a simple boost::infinity value or something, that would be useful. I have looked in the documentation, but have not been able to find anything so far.