Why is Zhang Xueliang called Zhang Xiaoliuko?

When he was born, Zhang won the battle, so he was named Double Happiness. Later, Zhang asked someone to tell Zhang Xueliang's fortune. The fortune teller said that he was destined to become a monk soon. Later, I found a temple and stabbed a man with grass. The straw man died instead of Zhang Xueliang. Later, a child ran around outside the temple. His family calls the child Xiao Liuzi. So Zhang Xueliang's nickname is Little Liu Zi.