This is a really difficult task as I see because of the blocking factor I decided the best solution is to go back to my roots in computer science
Since I am a Dinosaur that’s before OO I mean Knuth I am going to use a linked list I cannt create a cell pool because each record size is different in a vb file I am hoping not to fragment storage But going to give this a shot Thank you On Tue, Jun 30, 2026 at 9:55 PM Mike Schwab < [email protected]> wrote: > Through the 3350 there were some programs that wrote full track R0 > records to get a slightly larger block. > > On Tue, Jun 30, 2026 at 7:19 PM Michael Watkins > <[email protected]> wrote: > > > > I think I hear what you're saying - that a 32720-byte record might > occupy far few bytes when compressed and several could fit into a > 56632-byte physical record. I concede that SMF uses them, but unless > you're IBM, (or another software vendor) you're not writing a 65632-byte > physical record. This is not available to someone writing a problem program. > > > > -----Original Message----- > > From: IBM Mainframe Discussion List <[email protected]> On > Behalf Of Michael Oujesky > > Sent: Tuesday, June 30, 2026 6:39 PM > > To: [email protected] > > Subject: Re: Net bytes per track > > > > CAUTION: This email originated from outside of the Texas Comptroller's > email system. > > DO NOT click links or open attachments unless you expect them from the > sender and know the content is safe. > > > > Due to compression, yes there could be more than one 32720 byte logical > record in the 56632 byte > > physical record. Even if they were fixed length 32720 records. > > > > Michael > > > > At 06:04 PM 6/30/2026, Seymour J Metz wrote: > > >Content-Transfer-Encoding: base64No. But not all records are 32K in the > > >noormal run of things. > > > > > > > > >-- > > >Shmuel (Seymour J.) Metz > > >https://urldefense.com/v3/__http://mason.gmu.edu/*smetz3__;fg!!JJZmGcLP > > >LA!ffzBLup1PnWeGv_oP4SB8byOd9J5Ff8umRy31Qljuae4YSldPom7vXRy-UxSnOzuD7LW > > >CJqoLizjwVMd0Xrb_0t1iz4A2xha$ ×¢Ö·× ×(tm)ִשְ×'×¨Ö¸× Öµ×oe ×-Ö·×(tm) > > >� ֵ֣צַ×- ×(tm)ִשְ×'×¨Ö¸× ÖµÖ"×oe ×oeÖ¹Ö¥× > > >×(tm)Ö°×©Ö·× ×§ÖµÖ¼Öר > > > > > > > > > > > > > > >________________________________________ > > >From: IBM Mainframe Discussion List > > ><[email protected] on behalf of Michael Watkins > > ><[email protected]��[��Y\�^K� > > >[�HÌOE�� > > >���HPM > > >To: [email protected] <[email protected]> > > >Subject: Re: Net bytes per track > > > > > > > > >External Message: Use Caution > > > > > > > > >I also notice that the LRECL is 32720 and the records (FB) do not > > >appear spanned. Can there be more than one 32720-byte record in this > > >56,632-byte physical block? > > > > > >-----Original Message----- > > >From: IBM Mainframe Discussion List > > ><[email protected]Û^�Z[f Of Michael Watkins > > >Sent: Tuesday, June 30, 2026 5:18 PM > > >To: [email protected] > > >Subject: Re: Net bytes per track > > > > > >CAUTION: This email originated from outside of the Texas Comptroller's > > >email system. > > >DO NOT click links or open attachments unless you expect them from the > > >sender and know the content is safe. > > > > > >Sure, since the 1970s VSAM physical records have not corresponed 1-to-1 > > >with the CI-size. > > >Probably other access methods, too. That's just the one I'm keenly > aware of. > > > > > >The URL you cite directs me to a section of 'DFSMS Using Data Sets'. > > >For z/OS V3.2 (SC23-6855-70), this is p.386, 'Characteristics of > > >compressed format data sets'. However, the table with the SMF report > > >file is from another source. It has this line: > > > > > >ID DSORG RECFM LRECL BLKSIZE SMF14CIS > SMF14CMPTYPE > > >14 PS FB 80 32720 56632 3:ZEDC > > > > > >'SMF14CIS' is a field found within the SMF Type > > >14 record that indicates the physical block size of an extended format > > >data set. 56632 plus the > > >32 bytes appended for extended formatting is 56664, the track size. > > >Since creating these is ' > > >Nothing complex. Merely create the dataset with SMS compression. > > >Allocation and the SAM access method takes care of the details', what > > >allocation parameters are used to specify this extended format data set > > >whose physical record consumes the entire track with no inter-record > > >gapsB�B�B�KKKKSÜsY�[�[Y\��Y�KKKKKCB���om: IBM > > >Mainframe Discussion List > > ><[email protected]Û^�Z[�Ù^ZX�Y[�Z�\��CB��[�ï > > >¿½Y\�^K�[�H�2026 4:38 PM > > >To: [email protected] > > >Subject: Re: Net bytes per track > > > > > >CAUTION: This email originated from outside of the Texas Comptroller's > > >email system. > > >DO NOT click links or open attachments unless you expect them from the > > >sender and know the content is safe. > > > > > >Please see: > > ><https://urldefense.com/v3/__https://www.ibm.com/docs/en/zos/3.2.0?topi > > >c=sets-characteristics-compressed-format-data__;!!JJZmGcLPLA!dfwGSymF-D > > >Pi6jbNV2JZPFANiX3GmcW3d-5nqWl679R_NRKSC_KL9t8J-StNr50aZ7fgZYLeeHPxyd5NW > > >uJ-rTXdccGouSwF$ > > >�\�X�\�\�X��Ù^��\�\��Y�Ü>X]]H�]�@ IBM > > >Documentation The data format for a compressed format data set consists > > >of physical blocks whose length has no correlation to the logical block > > >size of the data set in the DCB, DCBE, and the data set label. The > > >actual physical block size is calculated by the system and is never > > >returned to the user. > > >However, the system maintains the user's block boundaries when the data > > >set is created so that the system can return the original user blocks > > >to the user when the data set is read. > > >SMF report of such files: > > >ID DSORG RECFM LRECL BLKSIZE SMF14CIS SMF14CMPTYPE > > > > > >14 PS VBS 32760 32760 27966 2:TAILORED > > >14 PS VB 4096 32760 27966 2:TAILORED > > >14 PS FB 80 32720 56632 3:ZEDC > > >14 PS FB 32752 32752 27966 1:GENERIC > > >Michael > > > > > > > > >At 11:30 AM 6/30/2026, Michael Watkins wrote: > > > >Please either expalin how to allocate an 'SMS compressed file with > > > >super-blocks that write full tracks of data' or point to some IBM > > > >documentation that explains this. > > > > > > > >I assume from the context of your previous remarks that 'full tracks > > > >of > > >]I�YX[��\�H\�H��[�ter-record gaps within the blocks; a > > >���V�OMM���\��entially. > > >B��v���B77VÖ�r��W"&Wf��W26���V�G2F�n't > > >make sense. Despite > > > >decades of mainframe infrastructure experience, I've never heard of > > >\Ë ]H�\�Z@nly don't know everything. > > > > > > > >-----Original Message----- > > > >From: IBM Mainframe Discussion List > > >P�KSPRS�T��ERV.UA.EDU> On Behalf Of Michael Oujesky > > > >Sent: Tuesday, June 30, 2026 11:18 AM > > > >To: [email protected] > > >Subject: Re: Net bytes per track > > > > > > > >Nothing complex. Merely create the dataset with SMS compression. > > > >Allocation and the SAM access method takes care of the details. > > > > > > > >Check you 14/15 SMF records for the actual physical size of blocks on > > > >DASD. 14/15 still have BLKSIZE, but is is now logical and not > > >\�X�[�B�С5������4(�4(�� 10:49 AM 6/30/2026, > Michael Watkins wrote: > > > > �X\�\�mud. How do I define a data set using full tracks of > > > > super-blocks using zEDC compressionÙ^��\��KHUP�@S > > > > specifying > > >��Q���\�\��[Û^�[]�HÈ(tm)H\��YÛ(tm)@d, but what > > >allocation > > > > \�[Y]\���[\�H ��\\�X��cks'? > > > > > > > > > Y�] ����X[�H�Ü(tm)��^Z[�X\�Hjust point to a > manual or > > > > �Y����]��[Y[��@s. > > > > > > > > > > B��������&�v����W76vR�����У�ɽ��% > 4 Mainframe Discussion List > > > > ><[email protected] On Behalf Of Michael Oujesky > > > > >Sent: Tuesday, June 30, 2026 10:28 AM > > > > >To: [email protected] > > > > >Subject: Re: Net bytes per track > > >�B���B���4�26��&W0sed data set. > > > > B��Ö6�V��4(��4(�At 10:13 AM 6/30/2026, Michael > Watkins wrote: > > >��IÛs]K� �Ñ-T�MS compressed files super-block and > write full > > > > ��X�ks of > > > > data'�]�[H\KX��\��X�H��Y�[�H�[�ard > > >������X��\��Y]��[�\�H Ù > [�X���\\�X�locks'? Please explain. > > > > > B���������&�v����W76pe----- > > >�����N�P�HXZ[���[YH\��\��[Û^\�P�KSPR@N@ > > >LISTSERV.UA.EDUÛfB���&V��b�bÖ6�V��V�W6���> > > >�[��Y\�^K�[�HÌOE��N� > > >�SCB���F�$ï¿½ï¿½Ô [email protected] > > > > > �X��XÝ^�N��]�]\�\��X�� > > > > > > > > > > >B�����9�Р�եÑ"����É*��M5L���� > > >I��Í*����les super-block and write full > ���X���Ù^]K���SIZE becomes logical (i.e. the buffer size > of ��]Hused between the applcation and the SAM access method. > > > > > > > > > ��YH�Q�M�T�[�HM�MH�Q��X�Ü(tm)�Ü^H@ctual > > > > physical size �Û^H�XÚ>B�����5�� ael > > > >��B���B����b�#��##b�Ö6�V�vF���2prote: > > > > > ï¿½ï¿½Û [�U�[�Ù(tm)\�Q[���[�Î^�\�M�Y\� > > >M��� bytes per track on a > > >��33��'WBF�RÖ?��VҢ��2BLKSIZE is 32,760 bytes and > > >only one ��&��6�v���`it on a track. > > > > > �B����F�Ö?�Ö-�RF�R��V�B�` data on a > > > > > track, half-track blocking is > > > > ��\X�[y used. There is a 668-byte inter-record gap on a native > > > > > ���L > > >]\��Û^H�[�JK�X�\È(tm)Y[��\icated on RAIDed > > > > ����H]�X�\�[�[�\��T�\��@tecture. This > > > > means there is a > > >��Ö?��VÒ?�b�G&6� BLKSIZE of 27998 bytes since > 668+(2x27998)=56664. > > > > > > > > > > > ��Ü^H]H�]�]X�]H�X�Ü(tm)�\�YX[�s half-track > > >��&��6���r�V�2#s�#�'�FR$ĵ4��Rsince 349 x > > >80 = 27920 and > > > > > �\�H\Û?Ý>��H[�B� > > > > > ��NN�Ü^H�LX�]H�X�Ü(tm)�B������ >Also > > >keep in mind that z/OS will append 32 bytes onto each block > > >��v�V�E4�E�S�U�DT�DTB�27V6�f�VB��Vning less > > >space for data ��&V6�&G2�2f��&��� > > B���4( > > > >> B��ⴴ���=ɥ������5��Í...�����-- > > > > > ����N�P�HXZ[���[YH\��\��[Û^\�P�KSPRS > > > > > �LISTSERV.UA.EDU> On > > > > ���Z[�Ù^���\�ZX�X[�B��> > > > ��[��[Û(tm)^K�[�H�K����HCB����F�$ï¿½ï¿ > > > ½[email protected] > > > > > ��X��XÝ^�N��]�]\�\�rack > > > > ��B����4UD���F��2VÖ��&�v��FVBg&�ï > > > > ¿½ outside of the Texas > > >��6��G&���W"w2VÖ�7�7FV�� > > >��D���B6Æ6�Æï¿½2�"�V�GF6��V�G2V��W72ï¿½ï¿ > > >½u expect them > > > > �����HH�[�\�[�Û>��Hï¿½Û [�t is safe. > > > > ��B���ä'¶VW��6VV��rg&�Ò'Sb�64 bytes per tack > > > > for 3390 pack how > > > > > �\�]]\�mined > > > > > �B�������)���I�������4(ï¿½ï¿ > > > > > ½ > > > > > > �Û^[Û<�[��K���]�N0�UT���H][H���\�\ > > > > > �i < > > >��V#ffVS�&#r�F�&2�&WVW7DÆ-7G6W'b�V�V@u> wrote: > > >��� ��� > The net bytes (i.e. longest record you can write > > >to that > > > > > ���X��H�\�Y\Èz@ access method as there is overhead > (control bytes). > > > > > > ���S�\È>ÝsYY���\]HH\��\Ý(tm)X�Ü(tm)which > > > > can > > >���f�B��G&6��W6��rU�5��6VPУ�> > > > >�Î<��\�Y�[��K���KÝOE���Ú<����ËsX�K���K�����en/zos/3.2.0? > > > > ��Â'���4(�� > > Unless you are using EXCP the hardware > > > > track capacity is �� irrelevant, > > >����9�9��9�8���9��9��9���&Ö�RFï¿ > > >½R0tual bytes per track (and > > > > ��f&�W2'�$ĵ4��R��� > > > > > ��B����=��QÕ"��)ո��0ï¿½ï¿½Ø ï¿½ÐEUR�(ï¿ > > > > > ½×?UK�AM Joseph Reichman < > > >���S�#cCVC62�F�&2� [email protected]> wrote: > > >������� Would anyone know how to get the net bytes per > > >track for a > > > > > ��33����� > > > > > >---------------------------------------------------------------------- > > >For IBM-MAIN subscribe / signoff / archive access instructions, send > > >email to [email protected] with the message: INFO IBM-MAIN > > > > > >---------------------------------------------------------------------- > > >For IBM-MAIN subscribe / signoff / archive access instructions, send > > >email to [email protected] with the message: INFO IBM-MAIN > > > > > >---------------------------------------------------------------------- > > >For IBM-MAIN subscribe / signoff / archive access instructions, send > > >email to [email protected] with the message: INFO IBM-MAIN > > > > > > > > > > > >---------------------------------------------------------------------- > > >For IBM-MAIN subscribe / signoff / archive access instructions, send > > >email to [email protected] with the message: INFO IBM-MAIN > > > > ---------------------------------------------------------------------- > > For IBM-MAIN subscribe / signoff / archive access instructions, send > email to [email protected] with the message: INFO IBM-MAIN > > > > ---------------------------------------------------------------------- > > For IBM-MAIN subscribe / signoff / archive access instructions, > > send email to [email protected] with the message: INFO IBM-MAIN > > > > -- > Mike A Schwab, Springfield IL USA > Where do Forest Rangers go to get away from it all? > > ---------------------------------------------------------------------- > For IBM-MAIN subscribe / signoff / archive access instructions, > send email to [email protected] with the message: INFO IBM-MAIN > ---------------------------------------------------------------------- For IBM-MAIN subscribe / signoff / archive access instructions, send email to [email protected] with the message: INFO IBM-MAIN
