The Absolute Energy, when in manifestation, when moving, is called Shakti.
When it is not moving, and is in Absolute Rest, it is called Shiv.
Here, we are not talking about the personality Shankara.
When it is in its potential form, absolutely at rest, without a single movement,
that completeness is Shiv, the Absolute Being. And, when it moves in kinetic form, when it begins to work, then it is Shakti.