2.23: What is Linker TOC overflow error 12?

There is a hard coded limit in the AIX 3.2.5 linker that is fixed in
AIX 4.1.  A kind soul donated the following information to help people
get the 3.2.5 fix

    The LPS (paperwork) 
      AIX TOC Data Binder/6000 #P91128
      Version 1.1
      Program Number 5799-QDY
      Reference No. GC23-2604-00, FC 5615
    Pre Reqs listed were AIX 3.2.5
      IBM C Set++ V2 (5765-186)

The above is not available any longer, see section 1.006.

You could also put some of the application code into shared libraries
or, in the case of gcc, use -mminimal-toc.