how to increase message buffer size?


New Member

Currently running OpenEdge 11.3 Workgroup database on Windows Server 2008. How do I increase the buffer size? The database is currently using the default (1024). Is there a parameter file that I need to put a larger value in? I've also read that since I'm on 11.3 then each client machine will have to have the new -Mm value updated as well. Would that be in the startup path for the shortcut?

Are the prefetch values updated that same as well (same place on server and client)?



Active Member
Client and Server must use same -Mm parameter. 8192 is commonly used.
Startup parameters are often listed in a pf file.

Rob Fitzpatrick Sponsor
The -Mm parameter (ABL client message buffer size) is both a client startup parameter and a 4GL connection broker startup parameter.

On the client size, you specify it with your other startup parameters (e.g. -q, etc.) on your prowin32/_progres command line or in a parameter file (e.g. _progress.exe -pf c:\path\

On the server side, you likely have your broker configuration in OEE/OEM, so you can set your -Mm value in the appropriate field there.

Note some constraints:
  • In 11.5 and earlier, the value of -Mm must be specified on both the client and the 4GL broker. The value must be the same on both sides. In later releases, you can specify it just on the broker side and the client will comply.
  • In 11.5 and earlier, every 4GL broker that the client connects to (e.g. if there are multiple databases) must use the same value of -Mm. In later releases, the -Mm values don't have to be the same between the 4GL brokers that a given client connects to.
The -prefetch* startup parameters are for 4GL brokers only.


11.3 is ancient and obsolete. You should have upgraded years ago.

Starting with 11.6 you only need to specify -Mm on the server. The client will be ignored.

If you are (temporarily of course) stuck on 11.3 you must specify -Mm on both the server and client command lines or in the relevant .pf files.