Program transitions (CALLs) between ‘ILCS’ program units or subroutines and ‘non-ILCS’ subroutines are prohibited.
ILCS runtime system modules (prefix IT0....) must only be contained once in the loaded application program. In other words, you must ensure that the ILCS modules are not linked repeatedly when linking by RESOLVE from the RTS libraries of the compilers, and that they are not loaded repeatedly when modules are loaded dynamically.
The highest available version of ILCS must always be loaded. The CRTE library always contains an ILCS.
Please refer to the user guide or service information such as the Release Notice and readme files of the compiler for information on whether the respective compiler version or the runtime system supports ILCS and if so which version. Information on the ILCS capability of compilers and runtime systems can be found in the Release Notice.
You will find a detailed list of the possible combinations of compiler options and RTS on "Compiler versions, runtime systems, KDCDEF options".
The CRTE manual contains examples of linking ILCS programs.