I understand ISS is using gyroscopes (CMG) to maintain its attitude. At the same time, I understand that ISS maintains constant attitude relative to Earth, i.e. its Z axis always points toward the center of the planet. Given the station's speed, it means ISS has to continuously change its attitude with speed of 4 degrees per minute (see 1).
This is where I am missing something. Gyroscopes, by definition, maintain certain attitude. Being stabilized by gyroscopes, shouldn't the station always be in the same "absolute" position, which would mean it has to be spinning relative to Earth?