Odesolve question

As part of an iteration program, Odesolve in a solve-block fails when one or more of the (positive) initial conditions is too large. Of course, a priori, I do not know how large is "too large." This failure causes the program to cease functioning, but the failure is itself information that needs to be returned to the program so that it continues to run. How can I guard against this failure? Any help will be much appreciated.