https://segment.com/docs/connections/sources/catalog/libraries/server/php/
Segment::init("YOUR_WRITE_KEY", array(
"consumer" => "lib_curl",
"debug" => true,
"max_queue_size" => 10000,
"batch_size" => 100
));
max_queue_size Number, optional | The max size of the queue, defaults to 10000 items.