in reply to
Placeholders(?) in the prepare statements for executing DBD::Sybase queries
I'm not sure why the responses above think you're using FreeTDS or MS SQL Server. From the trace output, you're using CT-Library directly. If that's so, the segmentation fault indicates you either have a version mismatch between your DBD::Sybase and CT-Library, or you've stumbled on a bug in the DBD -- although the latter is highly unlikely for such a simple code snippet.
If you're able, try to re-compile and/or re-install DBD::Sybase, and make sure your LD_LIBRARY_PATH points to the Sybase client version you used in the compilation.