The use of the “EXEC CICS” API is described in the CICS Application Programming Reference and the CICS System Programming Reference. It can be used in COBOL, C, C++, PL/I, or assembler programs. It cannot be used in Java programs.
In Java programs, you can use the JCICS classes to access CICS services and link to CICS application programs written in other languages. JCICS is described in The JCICS class library. (The types of Java program that you can write are listed in Types of Java application in CICS.)
You can write enterprise beans that use the interfaces defined in Sun Microsystem's Enterprise JavaBeans Specification, Version 1.1. CICS implements this specification by mapping program requests transparently to underlying CICS services. (You can also write enterprise beans that use the JCICS classes to call CICS services directly, but if you do so your beans will not be portable to non-CICS servers.)