Hi Frank, thanks for your feedback. Unfortunately, my error log files didn't show any issue. It is like ocs files are never generated because no process to generate these files is running (I have nothing related in crontab for example).
[Sun Nov 05 03:40:14.839132 2017] [auth_digest:notice] [pid 20576] AH01757: generating secret for digest authentication ...
[Sun Nov 05 03:40:14.873406 2017] [lbmethod_heartbeat:notice] [pid 20576] AH02282: No slotmem from mod_heartmonitor
[Sun Nov 05 03:40:15.105310 2017] [mpm_prefork:notice] [pid 20576] AH00163: Apache/2.4.6 (CentOS) OpenSSL/1.0.2k-fips PHP/5.4.16 mod_perl/2.0.10 Perl/v5.16.3 configured -- resuming normal operations
[Sun Nov 05 03:40:15.105343 2017] [core:notice] [pid 20576] AH00094: Command line: '/usr/sbin/httpd -D FOREGROUND'