1, from the definition of wholly-owned subsidiary:
A wholly-owned subsidiary refers to a company with only one corporate shareholders, and it is also a subsidiary wholly owned or controlled by the only parent company. A joint stock limited company needs more than 50 promoters. Therefore, a wholly-owned subsidiary cannot be a company limited by shares.
2, from the definition of joint stock limited company:
A joint stock limited company wants to divide the owner's equity into several shares, and shareholders enjoy rights according to the shares they hold. Only one wholly-owned subsidiary, corporate shareholders, is the parent company.
To sum up, a wholly-owned subsidiary should be a limited liability company.