Hello Lukas
The maximum buffer size for the particular device that Rene is using is actually 102400 KB or 102 MB. See the screenshot below:
Now keep in mind that the buffer is in the RAM of the Cisco device, which is usually not excessively large. The maximum sizes available for buffers will depend on the platform, the IOS and the available memory at the time.
For this reason, unlike Wireshark, the EPC feature is not designed to run for extensive periods of time. It should be used to capture specific traffic that is generated for the purpose of it being captured and analysed.
I hope this has been helpful!
Laz