Staging area is a temporary storage which is used to store file while integration is in execution. All the files being created during the integration run are flushed when the OIC integration completes(Success/Error) it's execution. Stage activity is used to access the staging area.
There is no limit while writing to Staging area but while reading only 10 MB size of messages can be read.
Solution to limitation:
To read file which has size more than 10 MB, we need to use Read File in Segments. The way around is - use this Read file in Segments action to read file serially, it reads in chunks of 200 and by-passes the 10MB limit.