Webservice request seen in wls acess logs but not in the application logs

Question

We have a soap webservice (written in java) that is hosted on weblogic in a clustered setup of two managed server nodes. We have a webserivce client calling our webservice inside a while loop and the loop does not break until a certain condition does not become true. Each webservice request will have the same chunk size and fileId a thrid field nextOffSet will differ based on what was sent in the earlier response.

The webservice receives a fileId and chunk size a part of the request and it returns the chunk size amount of data from the file specified and returns the data in the response. The response also contains a nextOffSet which will be set to -1 when there are no more bytes to return. This is the condition which causes the client to exit the while loop.

Now to the issue : The requests to the webservice can be traced to the wls access logs and the application logs until a certain number of calls but after that we do see the requests getting logged into the access logs but not the application logs. Also, the webservice client also never receives a nextOffSet with the value -1, so their while loop also does not exit.

Questions :

1. What are the caches available at wls managed server level?
2. How can i debug this issue further?