[SR-Users] memory problem

hi all I have kamailio 4.2.0 on Debian Jessie the parameters on startup of kamailio are : SHM_MEMORY=512 PKG_MEMORY=32 the server is dedicated to the kamailio SIP service with authentication and accounting on a separated db server the server process about 30/50 call setups per second everythings works good but after 5/6 days the processes lock and I received a lot of error log like these: <core> [rvalue.c:1710]: rval_str_add2(): rv eval out of memory <core> [msg_translator.c:362]: received_builder(): out of memory <core> [msg_translator.c:2717]: via_builder(): out of memory ... <core> [msg_translator.c:2423]: build_res_buf_from_sip_req(): out of memory; needs 514 ... <core> [data_lump.c:172]: insert_new_lump_before(): out of memory acc [acc_extra.c:267]: extra2strar(): extra2strar: out of memory. after a kamailio reboot evrethings works again for 5/6 days. what can I do to resolve?