recursively calling method (for object reuse purpose)

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recursively calling method (for object reuse purpose)

i have a rather large class which contains plenty of fields (10+), a huge array (100kb) and some unmanaged resouces which process long running task and i want to reuse it over and over again after each completion of task. below code illustrates the situation:

class ResourceIntensiveClass
{
    private object unmaganedResource; //let it be the expensive resource
    private byte[] buffer = new byte[1024 * 100]; //let it be the huge managed memory
    public Action<ResourceIntensiveClass> OnComplete;


    private void DoWork(object state)
    {
        //do long running task
        OnComplete(this); //notify callee that task completed so it can reuse same object for another task
    }

    public void Start(object dataRequiredForCurrentTask)
    {
        ThreadPool.QueueUserWorkItem(DoWork, dataRequiredForCurrentTask); //initate long runnig work
    }
}


class Program
{
    static object[] taskData = { "foo", "bar"};
    static int currentTaskIndex = 0;

    private static void OnCompleteHandler(ResourceIntensiveClass c)
    {
        currentTaskIndex = currentTaskIndex + 1;
        if (currentTaskIndex == taskData.Length)
        {
            Console.WriteLine("finished all task");
            return;
        }
        object data = taskData[currentTaskIndex];
        c.Start(data);
    }

    public static void Main()
    {
        ResourceIntensiveClass c = new ResourceIntensiveClass();
        c.OnComplete = OnCompleteHandler;
        object data = taskData[currentTaskIndex];
        c.Start(data);
    }

}

The problem here is, DoWork never returns after all tasks are completed. This cause a stockoverflow after some point. i could queue invocation of OnComplete on ThreadPool thus letting the DoWork return and let the runtime clear the call stack but i dont want to use extra resources. What would be the best option for me? (assume task progression is linear)(DoWork has to be executed on another Thread)