I am a new user of phoenics and I want to know how static pressure measures up in phoenics

I don't understand the question. The usual practice in PHOENICS is to solve for the static pressure (P1) relative to that applied at an outlet or entrainment boundary, ie the reference static pressure. In buoyant flows, it is the usual practice to remove the hydrostatic pressure so that the solved pressure (P1) is a pertubation (static) pressure about the hydrostatic equilibrium condition. In PHOENICS the default pressure unit is Pascals. For compressible flows, it is important to define the reference pressure via PRESS0, because this variable is used in the equation of state.