Allocating Bytes to Expand Memory Size

Hi,
Each time I attempt to upgrade to WP2.8.6, I get this error – “Fatal error: Allowed memory size of 33554432 bytes exhausted (tried to allocate 2355506 bytes) in /home1/thompso9/public_html/writegreen/wp-includes/http.php on line 1324”

I’ve attempted to find line 1324, but could not locate the byte size to increase the memory. What am I missing? Please advise. Thank you!