Man pages matching name curlopt_keep_sending_on_error in section 3:

CURLOPT_KEEP_SENDING_ON_ERROR.3.en	debian 10 / libcurl4-doc
CURLOPT_KEEP_SENDING_ON_ERROR.3.en	debian 11 / libcurl4-doc
CURLOPT_KEEP_SENDING_ON_ERROR.3.en	debian 12 / libcurl4-doc