Routines have three types of associated program sections:

    o  Code section-Contains the executable instructions of the
       routine. This section is typically read-only and executable.

    o  Data section-Contains data accessed by a routine. Typically,
       this is where variable data is stored. This section is
       typically nonexecutable, readable, and writeable.

    o  Linkage section-Contains a routine's procedure descriptor and
       the necessary linkage information for calling other routines,
       and for linkage to data not in the linkage section, if any.
       Also, constant data may be placed here. Typically, this
       section is read-only and not executable.

       The linkage section is considered a type of data section with
       the following function:

       -  Provides linkage information for calls made from a routine
          associated with the linkage section.

       -  Provides linkage information for data outside of the
          linkage section.

       -  Defines the associated routine's procedure descriptor so
          that calls can be made to the routine.

       -  Defines constant or static data.