为什么不抛出异常

当我运行下一个代码时，抛出一个 OutOfMemoryException：

static void Main(string[] args)
{
    for (int i = 0; i < 200; i++)
    {
        Stream filestream = new MemoryStream(Resources.File); // Resources.File is typeof byte[]
        ThreadPool.QueueUserWorkItem(ThreadProc, filestream);
    }
    Thread.Sleep(999999999);
}
private static void ThreadProc(object stream)
{
    // Document is 3rd party's class
    Document doc = new Document((Stream)stream); // OutOfMemoryException is thrown after 160 iterations
}

但是，如果我在"ThreadProc"方法中创建流 - 没有例外：

static void Main(string[] args)
{
    for (int i = 0; i < 200; i++)
    {
        ThreadPool.QueueUserWorkItem(ThreadProc, null);
    }
    Thread.Sleep(999999999);
}
private static void ThreadProc(object stream)
{
    Stream filestream = new MemoryStream(Resources.File);
    Document doc = new Document(filestream); // Exception is NOT thrown
}

为什么会有区别？