All Cobol program require a link-edit step after compilation, and it is normally part of the standard compile JCL. Today many Cobol programmers are probably not aware of the link-edit step anyway. Statically linked programs are resolved as part of the load module at link-edit stage (just after compilation), while dynamically linked programs are resolved at run/execution time. if a load module contains a statically linked module, and the statically linked module subsequently changes, the load module will still contain the original module instead of the new module. the load module will need to be link-edited again to incorporate the new module. Dynamically linked modules will not require a link-edit after each change to called modules, as called modules are resolved at run/execution time, so as long as the new dynamically linked module is in the steplib/joblib concatenation, it should resolve to the new module. As statically linked nodules are resolved in to the load module at linked-time, the are already part of the load module, and need not be read of the linklib at execution time. Statically linked modules require less overhead at execution time than do dynamically linked modules. However they do require more effective management at compile time and as link-editing of existing modules that are not part of a change may also need to be done. This increases risk to the production environment, so i much prefer that everything be dynamically linked as possible.

I googled and found it

http://publib.boulder.ibm.com/infocenter/pdthelp/v1r1/index.jsp?topic=/com.ibm.entcobol.doc_4.1/PGandLR/ref/rpsub08.htm