Use this optional LONG VARCHAR parameter to specify the name of a library to be unloaded. If no library is specified, all
external libraries that are not in use are unloaded. The default is NULL.
If an external library is specified, but is in use or is not loaded, an error is returned. If no parameter is specified, no
error is returned.
The library name must match exactly the path and letter case of the original library specification. For example, the library
name must match exactly the string following the '@' in the following EXTERNAL NAME clause.
EXTERNAL NAME 'xp_replicate@c:\\sqlany\\samples\\sqlanywhere\\ExternalProcedures\\extproc.dll'