The first couple lines of the stack trace mention issues (overflow, stackguard corruption) with the stack.
You could try increasing your stack [guard] sizes via: sp_configure 'stack size' and sp_configure 'stack guard size'. These settings apply to each connection and take away from max memory so you don't want to set these too high; I'd suggest doubling the current values for the first change and see if this eliminates the stack trace.
I'd also suggest spending some time debugging the trigger code, eg, how many nested levels is it reaching (select @@nestlevel)? With ASE 12.x I believe the max nesting level was 16 and while I'd expect the dataserver to abort the process if you attempt to go to level 17, I wouldn't be surprised if an attempt to go to level 17 could cause a stack trace, too.
