Max Filesize for PHP copy

[Ashley]

I was using a script to copy a file from one location to another.  It 
was working great (but was only testing with small files under 1MB) and 
then when I tried uploading a file that was a little over 4MB the server 
abended with the message "Cache memory allocator out of available memory".
I looked in the PHP.ini file and changed the max filesize to 5MB and 
tried to copy the same file.  It worked, but I received the same 
message, but it didn't abend.
I don't think that this is normal and would appreciate any suggestions 
as to a better method or an explanation as to what may be causing this.

NW6, PHP 4.2.4, Apache 2.0.48

Thanks in advance,
Ashley