When working on a large application when using composer you can sometimes hit an error that you exhausted the memory limit of composer.
PHP Fatal error: Allowed memory size of XXXXXX bytes exhausted <...>
You can resolve this by increasing the PHP memory_limit.
But if you don't want to increase the PHP memory_limit but still want to increase the memory usage to composer you
can use another environment variable of COMPOSER_MEMORY_LIMIT which can be used as below.
COMPOSER_MEMORY_LIMIT=-1 composer install