The simplest way to implement the EXTFH interface is to specify the file name or absolute path of a single EXTFH shared object library as the value of A_EXTFH_LIB. When you use this method, the runtime loads the specified library in order to find the necessary EXTFH function or functions.
For example, to use the EXTFH library supplied with TXSeries CICS for DB2, specify:
A_EXTFH_LIB /usr/lpp/cics/lib/libxfhdb2sa.a(libxfhdb2_shr.o)
where "libxfhdb2_shr.o" contains the entry point to the DB2 EXTFH library and resides in the "libxfhdb2sa.a" AIX archive. In this case, if your LIBPATH variable includes the path where the library resides, you can omit the path; otherwise, include the path as part of A_EXTFH_LIB.
You can also specify the EXTFH library as an environment variable. For example, you can specify the same EXTFH library for accessing DB2 files from TXSeries using:
export A_EXTFH_LIB="/usr/lpp/cics/lib/libxfhdb2sa.a(libxfhdb2_shr.o)"
An AIX archive file (".a") can contain shared objects. You must specify the shared object in parentheses after the archive name unless you link to the archive.