sorry I think you have two different diciplines here. an In-Stream procedure is a JCL idea associated with the PROC statement. an in-line procedure is a COBOL concept associated with a PERFORM.

An in-stream PROC is defined right in the jcl stream and doesn't reside in the proclib. This is an older technique associated with punched cards but it is still in use with setup and installation programs from vendors.

for the in-line perform instead of:

perform add-paragraph until switch 'y'

you can code

perform until switch 'y'

body of code

end-perform

body of code is the code from add-paragraph appearing in-line (ie right in the perform) instead of in a separate paragraph (out of line code)

Instream proc is a procedure coded within the JCL. It is not stored in a PROCLIB. Generally when the proc is not to be made a reusable piece of code it can be coded as instream proc.

there is nothing called as inline proc. Instead another type of procs are cataloged procs - these are coded as members (part of proclib) which are called in the JCL using an EXEC statement. These are the generally preferred procs as the same code can be resused and you can override parameters in proc by passing values in JCL.