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?