Please see the design constraint documentation in the 6.4 Reference Guide under the topic "LE-Enabled Support".
When PARM ENVIRONMENT(COBOL) is specified in a CA Easytrieve Plus program (or in the Options Table), the CA Easytrieve Plus initialization establishes either the LE/COBOL or the COBOL II environment. You can control which environment is established by your placement of the LE runtime library (SCEERUN in z/OS or SCEEBASE in VSE). In order to run in LE mode, the LE runtime loadlib must be in the linklist, joblib, steplib, or LIBDEF preceding any other COBOL runtime libraries. If you do not do this, the LE setup is not done. If the LE runtime lib members are not found, the COBOL II environment is established.