Nested /COPY or /INCLUDE
Nesting of /COPY and /INCLUDE directives is allowed. A /COPY or /INCLUDE member may contain one or more /COPY or /INCLUDE directives (which in turn may contain further /COPY or /INCLUDE directives and so on). The maximum depth to which nesting can occur can be set using the COPYNEST control specification keyword. The default maximum depth is 32.
Tip:
You must ensure that your nested /COPY or /INCLUDE files do not include each other infinitely. Use conditional compilation directives at the beginning of your /COPY or /INCLUDE files to prevent the source lines from being used more than once.
For an example of how to prevent multiple inclusion, see Figure 1.