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
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)
SYSPRINT: All system output will appear under this DD card. Suppose you are copying a VSAM file using IDCAMS. Then, number of records processed, highest condition code etc.. will appear under sysprint. You cannot customise SYSPRINT output.
SYSIN: This is nothing but SYStem INstruction. Suppose, you want to sort a file on certain key. You have to have following command under SYSIN.
SORT FIELDS = (starting-col,length,data-type,A/D)
SUM FIELDS = NONE
DUMMY: Mainly used where user is intended to simulate a program without creating an output file.