casinh (and so casin, which calls casinh) suffers spurious overflows on large arguments from internal calculations. E.g., on x86_64, casinh (0x1.fp1023 + 0x1.fp1023i) raises spurious INVALID and OVERFLOW exceptions and returns a result that wrongly has infinite real part.
Fixed for 2.18 by:
Author: Joseph Myers <email@example.com>
Date: Mon Jan 7 14:59:53 2013 +0000
Fix casinh, casin overflow (bug 14996).