By default, the server returns a maximum of 500 records per search.  To increase this limit, you must edit the file /etc/openldap/slapd.conf while logged in as the root user.  These steps describe one way to do this:
1. Log in to the server as root. If you need help with this step, see technical document 106290, "Mac OS X: About the root User and How to Enable It" 
2. Open TextEdit. 
3. Click the Finder icon in the Dock.
4. Choose Go to Folder from the Go menu. A sheet appears.
5. Type: /etc/openldap/ 
6. Click Go.
7. Locate the file named: slapd.conf 
8. Drag this file onto the TextEdit icon in the Dock. 
9. Add this line to the end of the file:
sizelimit <max number>
For example, to allow a maximum of 15000 records, enter: 
sizelimit 15000
10. Save the file. 
11. Quit TextEdit. 
12. Log out.
This should allow you to increase the number of records returned. If it does not, follow these steps:
1. Drag the slapd.conf file to the Trash.
2. Make a copy of: slapd.conf.default 
3. Rename the copy to: slapd.conf 
4. Repeat the steps above, being sure to make no other changes to the file.
Type the command "man slapd.conf" in Terminal for more information on the slapd.conf file.