Because of a dramatic variation in the plasma density along the radius of a star, the process of magnetic field freezing occurs there in two substantially different regimes: in the lower (collisional) layers it is caused by generation of circular currents , compensating variations of the magnetic field in the co-moving (with plasma) flux tubes; whereas in the upper (collisionless) layers the magnetic field freezing is maintained by synchronism of the plasma drift, due to a divergence-free character of the magnetic field and an electric equipotentiality of the magnetic field lines [e.g. Yu.V. Dumin, Solar Sys. Res., v.32, p.323 (1998)]. Transitional region between the two regimes of freezing is a natural place for reconstruction of the current systems and, therefore, the energy release. In the particular case of the Sun (where all parameters are known with a reasonable accuracy), predicted position of the transitional region corresponds very well to the zone of sharp temperature increase in the base of the solar corona [Yu.V. Dumin, Adv. Space Res., v.30, p.565 (2002)].