code: public void setIdleMin(int min)
    {
      if (min == _idleMin) {
        // avoid update() overhead if unchanged
        return;
      }
      
      if (min <= 0) {
        min = DEFAULT_IDLE_MIN;
      }
      
      if (_threadMax < min)
        throw new ConfigException(L.l("IdleMin ({0}) must be less than ThreadMax ({1})", min, _threadMax));
      if (min <= 0)
        throw new ConfigException(L.l("IdleMin ({0}) must be greater than 0.", min));
  
      _idleMin = min;
      
      update();
    }
docs: Sets the minimum number of idle threads.