The contents of the holding buffer can be searched or displayed using the if, until, peek, or show buffer commands. If you use if or until to look for an expected prompt or response from the remote system, the holding buffer will be emptied out up to and including the matched characters if they're found. If no match is found, the buffer remains unchanged. If you use the peek command, the holding buffer will be empty when peek is through. If a get file is open, the characters removed from the holding buffer will be written into the get file.
The holding buffer is about 3,000 characters big. If the buffer fills up, characters from the beginning of the buffer will be removed (and written to a get file if one is open) to make room for the newly received characters.
The holding buffer contains only characters received from the remote system. If the remote system is full duplex, it will echo characters you send, so the echo of your commands will appear in the holding buffer. If it is half duplex, what you send will not be contained in the holding buffer.