You want to understand what http.client.persistence(preserve) mean and how it works.
Reference: Please refer to page 356 of the SGOS CPL guide: https://symwisedownload.symantec.com//resources/sites/SYMWISE/content/live/DOCUMENTATION/10000/DOC10455/en_US/CPL67.pdf?__gda__=1556006573_b6751949b8de84541501b891dec052af
The preserve option reflects the server's persistence to the client connection. In other words, if the server has chosen not to maintain persistence (and closes its connection after serving its response to the first request), the proxy will force the client to use a new connection for each request, and conversely, if the server chooses to maintain persistence, the proxy will attempt to do so on the client side also. (Note however that a client configured to never use persistence, for example a browser or application which only do HTTP 1.0, will ignore such attempts and use a new connection for each request regardless).