为什么每次调用时新线程的堆栈大小都不同？

如何解决为什么每次调用时新线程的堆栈大小都不同？

我指定了`-Xss200k，因此每个线程的堆栈大小应为200 KB。创建新线程时，它允许我在StackOverflow到达之前执行大量的嵌套函数调用。我相信我应该不断收到一个崭新的线程的调用，该线程的堆栈中充满了N个帧。但是，每次运行之间可能进行的递归调用的数量各不相同：

StackOverflowError.... recursiveCalls = 2257
StackOverflowError.... recursiveCalls = 2266
StackOverflowError.... recursiveCalls = 2261
StackOverflowError.... recursiveCalls = 2267
StackOverflowError.... recursiveCalls = 2262
StackOverflowError.... recursiveCalls = 2243
StackOverflowError.... recursiveCalls = 2278

class RecursionCheck {
    int recursiveCalls;

    void callItself() {
        recursiveCalls++;

        if (recursiveCalls % 1000 == 0) {
            System.out.println("recursiveCalls = " + recursiveCalls);
        }

        try {
            callItself();
        }
        catch (StackOverflowError r) {
            System.out.println("StackOverflowError.... recursiveCalls = " + recursiveCalls);
        }
    }
}

public class RecursionExperiment {
    public static void main(String[] args) {
        new Thread(() -> new RecursionCheck().callItself()).start();
    }
}