  Using numerical and analytical methods implemented for different models we
conduct a systematic study of thermodynamic properties of pairing correlation
in mesoscopic nuclear systems. Various quantities are calculated and analyzed
using the exact solution of pairing. An in-depth comparison of canonical, grand
canonical, and microcanonical ensemble is conducted. The nature of the pairing
phase transition in a small system is of a particular interest. We discuss the
onset of discontinuity in the thermodynamic variables, fluctuations, and
evolution of zeros of the canonical and grand canonical partition functions in
the complex plane. The behavior of the Invariant Correlational Entropy is also
studied in the transitional region of interest. The change in the character of
the phase transition due to the presence of magnetic field is discussed along
with studies of superconducting thermodynamics.
