Can someone help me understand what happens as I increase the memory_limit in my php.ini file??

I have been getting a "White Screen of Death" when uploading photos over maybe 150KB.

After some research, it seems like it could be related to a lack of resources in my php.ini file, so I made the following random change...

Code:
;;;;;;;;;;;;;;;;;;;
; Resource Limits ;
;;;;;;;;;;;;;;;;;;;

max_execution_time = 30     ; Maximum execution time of each script, in seconds
max_input_time = 60	; Maximum amount of time each script may spend parsing request data
;memory_limit = 8M      ; Maximum amount of memory a script may consume (8MB)
;2013-03-23
memory_limit = 500M      ; Maximum amount of memory a script may consume (500MB)

Oh, BTW, my php.ini file also already had this code...
Code:
post_max_size = 500M
upload_max_filesize = 500M

Based on some preliminary testing, this seems like it could have been the issue. (My script sets the upload limit at 2MB, but I was able to upload a 1.9MB photo just now.)

Currently, I am just working locally on my MacBook with MAMP.

I'm not sure if making a change like I did could cause other undesirable side-effects including Global-Thermal-Nuclear-Meltdown?!

Please enlighten me for working locally on my laptop, and moving forward when I configure my VPS for my live website.

Thanks,


Debbie