You can write CICS applications in COBOL (OK), C (huh), C++ (makes sense), Java (hmm, I guess IBM put a lot of effort behind Java, yeah), assembler (of course, I think this is the normal choice), PL/I (heh, of course), REXX (somewhat unsurprising, since that was the standard post-JCL IBM scripting language), PHP (WTF?!)
REXX has “compound variables” that are associative arrays, like Perl hashes or Python dicts.
Chen-Ho encoding is a prefix code that stores three decimal digits per ten bits, using bitfields and variable encodings rather than multiplication and division. It leaves, as you would expect, 24 possible bitstrings unassigned. It is almost, but not quite, a lexicographical-order-preserving encoding.
Iterating a #math function half a time.