How do I debug a dying php process?

I’m using PHPExcel 1.7.6 on PHP 5.2.14.

When I turn on cell-caching with the following configuration:

[php] $cacheMethod = PHPExcel_CachedObjectStorageFactory::cache_in_memory_gzip;

my process runs (I have some timing/memory measurement code that I output to a log) but it eventually just dies. I checked my error log but there’s nothing there. When I run with an alternate configuration, it doesn’t die. I’d like to track be able to track down why this is dying. How would I do this?

I can give more code/details if that would be helpful.