Last month, I was building a web application that collected a lot of data via form submissions. I wrote a method to export attachments and form data by zipping them all together.
It worked for a smaller archives but as the records grew larger, I got a fatal error which said that I've exhausted the PHP's memory limit.
So, I found an easy way to increase the memory limit to 1024MB (1GB) like this:
<?php ini_set('memory_limit', '1024M'); ?>
Before you write this stub in your script, make sure you have enough resources in your system or else, it'll go splat!