When the certificate has been issued, the persons named therein, in case they shall not have subscribed for the entire capital stock, may open books of subscription to complete the subscription to the capital stock of the company, in such manner and for such amount per share as they may deem proper and expedient, and may receive the subscriptions until the entire capital stock is subscribed. In no case shall the capital stock be increased except as provided in this chapter.
OCGA § 52-5-7