The setting was introduced as part of an investigation into an issue where the iPrint server seemed to be having a difficult time servicing iPrint client requests, specifically those related to drivers.  Symptoms included iPrint printers showing Available and then showing Not Available on the PC.  The thought was that by having the ability to increase the driver worker threads, the symptoms would be resolved.  From what I recall, it did not make a difference.  However, as a result of that investigation, the following article was published, https://support.microfocus.com/kb/doc.php?id=7006806.  

Thank you Robert,

I confirm this settings is not helpful.

I also tried to tune server-tuning.conf, but this remains empirical.

When loaded our iPrint  server is currently facing a series of cores generation both for ipsmd and httpd-prefork

If you are experiencing cores related to the ipsmd process, you will need to open a case.  Make sure you're running the latest OES/iPrint Appliance code. 

A case has been opened on March 27th ;-)