As others have pointed out, the problem is in your use of system().

I believe, though I don't have time to confirm, that you could do the following:

system("cmd /c start dbeng9", @engstartargs);  # SHOULDN'T HANG NOW
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Though, of course, this is a win32-specific solution. The fork() solutions suggested by others would be more cross-platform (though with the hard-coded path names does it really matter?)

BTW: the sqlanywhere newsgroups are always available ;-)