Texas Civil Practice and Remedies Code - CIV PRAC & REM § 11.055. Security

(a) A court shall order the plaintiff to furnish security for the benefit of the moving defendant if the court, after hearing the evidence on the motion, determines that the plaintiff is a vexatious litigant.

(b) The court in its discretion shall determine the date by which the security must be furnished.

(c) The court shall provide that the security is an undertaking by the plaintiff to assure payment to the moving defendant of the moving defendant's reasonable expenses incurred in or in connection with a litigation commenced, caused to be commenced, maintained, or caused to be maintained by the plaintiff, including costs and attorney's fees.