Use the AMBLIST service aid to find out the AMODE and RMODE of a load module. The module summary produced by the LISTLOAD control statement contains the AMODE of the main entry point and the AMODE of each alias, as well as the RMODE specified for the load module. Refer to z/OS MVS Diagnosis: Tools and Service Aids for information about AMBLIST.
You can look at the source code to determine the AMODE and RMODE that the programmer intended for the program. However, the linkage editor or the loader can override these specifications.