MTOM attachment size limit in WebSphere application server

I have a web service with MTOM enabled that receives binary attachments as part of the message payload from the client facing applications. The service is deployed on WebSphere application server. There is no SOAP message handler in place. However, I happen to notice that attachments with greater than 10 MB in size are being dropped by the server or not processed. Basically WebSphere stores the temporary attachments in "IBMTmpCD" folder with *.att filename extension. In the logic when the service attempts to grab the input stream from the Data Handler, the File Not found Exception is thrown. As a result the BLOB does not get created that further causes issues.

My question is that is there a Web Service Proxy settings or any other settings that control the MTOM attachment size limit. I am using MTOM annotation with default values on the service implementation. If a client application sends an attachment of size less than 10 MB then all is well; but when any attachment greater than 10 MB seems like is being blocked by the server or not processed. I have also monitored the SOAP message using TCP/IP monitor, the MTOM attachment message is formed correctly as expected.

Also, if I disable MTOM then attachments greater than 10MB is successfully received and processed by the server.

Environment: Java 7 WebSphere 8.5

Any help on this issue is very much appreciated.