When to dispatch_release()?

I'm fairly new to GCD and was trying to find an answer to this. Assuming I have the following code:

dis开发者_运维技巧patch_queue_t queue = dispatch_queue_create("queue", NULL);
dispatch_async(queue, ^{
    // do some stuff
});

Where in the code should I release the queue? Inside or outside the block?

Outside the block. I'm fairly certain you don't have to wait for the async block to finish as GCD will retain the queue.