JVM - keystore - cacert file vs. NWA - key storage - TrustedCAs

Hello,

could anybody clarify in detail, when should we use and add certification as trusted to JVM keystore: cacerts file and when should we add them to "TrusdtedCAs" key storage in NWA? Specially at SAP PI system (see communicaiton channel with different adapters: JMS, HTTPS, SOAP, etc.) would be intresting for me.

Thanks in advance!