To estimate the fatigue endurance limit at the micro-scale two unlike dislocations gliding in a channel of a persistent slip bands are considered. The dislocations are modeled as moving planar flexible curves. The objective of the simulations is to determine the averaged stress in the channel needed for the dislocations to escape one another using statistics of encounters of such dislocation pairs. We employed an iso-strain approach, i.e. the assumption that the total strain everywhere in the channel is the same.