Oebs 12.1.0 oacore, forms for Java with high cpu and high memory

hello,

     We have installed Oracle Application E-Business 12.1.0 then I have several process with java on my  application's server.

there are my concurrente program which started all. (oafm, forms, xml-publisher, oacore )  

( See my process )

/oracle_applis/appcnprd/apps/tech_st/10.1.3/appsutil/jdk/bin/java -DCLIENT_PROCESSID=19299 -server -verbose:gc -Xmx1024M -Xms512M -XX:MaxPermSize=256M -XX:NewRatio=2 -XX:+PrintGCTimeStamps -XX:+UseTLAB -XX:+UseParallelGC -XX:ParallelGCThreads=2

1 - I see that every process java have got 1,5Go memory is it necessary ? how may I know what do I need ?

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND　

19309 appcnprd 20 0 1596m 1.3g 5928 S 6900.0 8.6 4:09.46 java