You can obtain a linkage editor storage map, and a listing of linkage editor diagnostics, to help you determine the reasons for particular errors in your program. To do this, use the ACTION MAP linkage editor control statement. If SYSLST is assigned, ACTION MAP is the default. You can specify ACTION NOMAP if you do not want the linkage editor to produce the storage map.

Detecting Link-Edit Errors: After link-editing, you receive a listing of diagnostic messages on SYSLST. Check the linkage editor map to make sure that all the object modules you expected were included.

Unresolved “weak” external references (WXTRN) can be ignored. However, all “strong” external references (EXTRN) should be resolved for a phase to run correctly.

You can find a description of linkage editor messages in VSE/ESA Diagnostic Tools.