You may need to allocate more memory to PHP, but IIRC there’s no way to do that via bbPress.
How can I allocate more memory to php? Can you be more exhaustive?
I guess it’s just an error from your webhost or you need a better webhost
No, it’s a known issue with WP and php memory, so I’m not surprised to see it crop up with bb as well.
Read here:
http://www.narfstuff.co.uk/2008/03/14/php-memory-and-wordpress/
http://perishablepress.com/press/2008/02/19/improve-site-performance-by-increasing-php-memory-for-wordpress/
But seeing as you don’t know how to do that now, I suspect you’ll need to talk to your webhost for help. If you have a good host, they’ll help you out 
Dear friends,
is not the fault of the webhost but bbpress. I want to know how to set its memory capacity. Usual procedure with WordPress (WP-MEMORY LIMIT).
Yes, it’s an issue with bbPress. It’s an issue with WordPress too. It’s an issue that means you need more memory. The memory limit (see the WP Codex for more on WP_MEMORY_LIMIT) means you need to increase your blog’s PHP memory limit. Why they call it limit and not something that implies ‘adding’ I don’t know.
Which usually means your webhost hasn’t allocated enough to run WP/BB. Which means it’s actually an issue with your webhost that MAY be work-aroundable with manual tweaking.
While you’re welcome to try BB_MEMORY_LIMIT (which is the logical name for it), I don’t think it exists.
If you actually read the links I gave you, you’d know that PerishablePress (a fantastic resource) mentions you may be able to increase memory limits by editing wp-config.php like so:
<?php
@ini_set("memory_limit","16M");
Try that on bb-config.php and see how it works.
You’re probably going to need to dig into your php settings to see how much memory you’ve got right now, and how much you have to play with. You’ll need to savvy up on your error logs too, to see where it’s barfing.
Thanks for your help. The problem was created by a incopatibile plugin with my version of bbpress (term of service). It was not a problem of memory as I thought.
