CentOS 6.2 there is no slapd.conf after installating openldap

Note that OpenLDAP no longer reads its configuration from the /etc/openldap/slapd.conf file. Instead, it uses a configuration database located in the /etc/openldap/slapd.d/ directory.

Source: The official upstream documentation for RHEL7

The slapd configuration consists of LDIF entries organized in a hierarchical directory structure, and the recommended way to edit these entries is to use the server utilities described in Section 16.1.2.1, “Overview of OpenLDAP Server Utilities”.

In other words, RHEL6 (and CentOS6) no longer has a single slapd.conf file to configure openldap. You should use the tools lised in section 16.1.2.1 to configure openldap.

If you have an old config you wish to import, you can do that using this command:
slaptest -f /etc/openldap/slapd.conf -F /etc/openldap/slapd.d/