为什么要紧急恢复buf大小为64 << 10？

I see so many code snippets which panic recover in golang. Just looks like:

func PanicRecover(c context.Context) {
    if e := recover(); e != nil {
        const size = 64 << 10
        buf := make([]byte, size)
        buf = buf[:runtime.Stack(buf, false)]
        logs.CtxError(c, "Error: %s", string(buf))
    }
}

I want to know why buffer size is always 64 << 10.