how to set an optimal cachesize into openldap

Hello

My openldap server is always crashed with segmentation fault exit. exemple slapd[6814]: segfault at 8 rip 4af0f2 rsp 451c0530 error 4

I want to tune this server by putting a better cachesize.

The size of the openldap database into system is 125 MB

The siize of id2entry file is about 22M The size of db2intery file is 6,7M

I read on the Administration openldap guide that i can execute db_stat -m to look on the cachesize used by slapd. This size is increasing every hour. In the morning it was on about 240 M on the evening, it increase until 400 M

What does it mean and how to deal with that

Thanks