Buffer size and available space of SSL channels


I want to get and prefer to set WIP_COPT_SND_BUFSIZE and WIP_COPT_SND_LOWAT on SSL channels. These options are only available on TCP sockets. Is there the possibility to get those information about a SSL socket?
Are there default values? Where could I find them?

WIP_COPT_SND_BUFSIZE and WIP_COPT_SND_LOWAT are not supported in SSL channels.
Anyway I tried with wip_getopts API, even though I get an error message (WIP_CERR_NOT_SUPPORTED) I am able to read the WIP_COPT_SND_BUFSIZE as 5840 and WIP_COPT_SND_LOWAT_value as 0 (can be default values)