I suppose one might increase the likelihood of non-optimization by putting the dummy field AFTER the copyright string.
Charles -----Original Message----- From: IBM Mainframe Discussion List [mailto:IBM-MAIN@LISTSERV.UA.EDU] On Behalf Of John Gilmore Sent: Thursday, October 31, 2013 10:55 AM To: IBM-MAIN@LISTSERV.UA.EDU Subject: Preventing the deletion of unreferenced strings by optimizing compilers I wanted to test my notion before presenting it, and it does turn out that embedding an unreferenced value in a structure (COBOL record) at least one other element of which is referenced in an executable statement ensures that that structure will not be deleted. A PL/I example declare 1 copyright_block static, 2 false aligned bit initial('0'b), 2 true aligned bit initial('1'b), 2 copyright_text character(38) initial ('C copyright 1591 by John Harington, Kt') ; found = false ; /* ex hyothesii */ linear_search: do i = lbound(A,1) to h bound(A,1) ; . . . found = (A(i) = s) ; if found then leave ; /* match? */ . . . end linear_search ; Here the single reference to copyright_block.false in an executable statement ensures that the structure copyright_block will not be deleted (or trimmed) by an optimizing compiler. ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
