-qcompact

In IBM® XL C/C++ for AIX® 16.1.0 or earlier releases, the -qcompact option avoids optimizations that increase code size.

In IBM Open XL C/C++ for AIX 17.1.2, the -Oz or -Os option provides a similar function to control output code size, but -Oz and -Os work only at the -O2 optimization level. For example, if you specify -O3 -Os, -O3 is overridden.

When you port your program from IBM XL C/C++ for AIX 16.1.0 or earlier releases to IBM Open XL C/C++ for AIX 17.1.2, reevaluate the size of the output generated by IBM Open XL C/C++ for AIX 17.1.2. If reduction in code size is required, try using the -Os option and note any performance trade-offs. If further reduction in code size is required, try using the -Oz option.