The real voltage source can be represented as serial connection of ideal vdc and imperance Z (this is zero for ideal case). Current source is usually represented as parallel connection of ideal current source and admittance. Admittance Y = 1/Z. In ideal case Y=0, which gives Z = infinite. Thus you can use admittance instead of impedance.
The Internal impedance of Current source in Bounded and Convergent System should be THE LARGE possible value. So idc of analogLib in Cadence Virtuoso Design Environment would be....?
I presume, idc is not the impedance parameter, just current. It surely has to be finite.
Secondly. Circuit simulators have general parameters limiting the impedance of any node to a large final value, respectively the admittance to small value > 0. They also affect the behavior of sources. Without specifying an impedance explicitly, it's still limited.