On Wed, 18 Aug 2021 08:46:43 +0000, Seymour J Metz wrote: >Aftermarket books generally get things wrong; that's why I prefer to use the >reference manuals as tutorials. BTW, can you spot what else is wrong with that >passage? > o Should ENQ specify EXC? (Or other locking mechanism such as CS.)
o Should "user" be "job", "thread", or ??? o In some cases such as an in-module RSA, restore is unnecessary. o ... ________________________________________ > >FWIW From "MVS Systems Programming" by Dave Elder-Vass (IBM McGRAW-HILL >SERIES, ISBN 0-07-707767-9, 1993): > >[Section 3.7.2:] "In theory, self-modifying sections are allowed in >re-entrant programs as long as they are preceded by an ENQ, followed by >a DEQ, and restore the modified section to its original value before >issuing the DEQ. These restrictions ensure that only one user can use >the modifying section of code at any one time; however, it introduces >potential delays for widely shared programs and is not recommended." -- gil ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
