Blocked SYSIN/SYSOUT
jn: https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.4.0/com.ibm.zos.v2r4.hasc300/has2z1_Use_of_unblocked_records_for_SYSIN_and_SYSOUT_data_sets.htm You should not block SYSIN and SYSOUT data sets because the SAM (sequential access method) compatibility interface will increase overhead by unnecessarily deblocking and blocking data sets. I didn't know that. Should I have RTFM? Is SDB aware of that? If BSAM, is this offset by more calls to WRITE/READ? BLKSIZE is incompatible with DD */DATA, perhaps because the programmer is expected to use F/V rather than FB/VB -- gil -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Blocked SYSIN/SYSOUT
On 2020-11-20 12:32, Paul Gilmartin wrote: jn: https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.4.0/com.ibm.zos.v2r4.hasc300/has2z1_Use_of_unblocked_records_for_SYSIN_and_SYSOUT_data_sets.htm You should not block SYSIN and SYSOUT data sets because the SAM (sequential access method) compatibility interface will increase overhead by unnecessarily deblocking and blocking data sets. That seems strange. Who said that? In what context? In the old days, it was important to block SYSOUT. Unblocked input and output contributed to disc threshing, which resulted in reduced performance of the disc system as well as slowing down output speed. I didn't know that. Should I have RTFM? Is SDB aware of that? If BSAM, is this offset by more calls to WRITE/READ? BLKSIZE is incompatible with DD */DATA, perhaps because the programmer is expected to use F/V rather than FB/VB -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
Re: Blocked SYSIN/SYSOUT
On Fri, 20 Nov 2020 12:42:34 +1100, Robin Vowels wrote: >On 2020-11-20 12:32, Paul Gilmartin wrote: >> jn: >> https://www.ibm.com/support/knowledgecenter/en/SSLTBW_2.4.0/com.ibm.zos.v2r4.hasc300/has2z1_Use_of_unblocked_records_for_SYSIN_and_SYSOUT_data_sets.htm >> >> You should not block SYSIN and SYSOUT data sets because the SAM >> (sequential access method) compatibility interface will increase >> overhead >> by unnecessarily deblocking and blocking data sets. > >That seems strange. Who said that? In what context? > Indeed. IBM. WWW. >In the old days, it was important to block SYSOUT. >Unblocked input and output contributed to disc threshing, >which resulted in reduced performance of the disc system >as well as slowing down output speed. > That may have been the Bad Old Days, before ASP/HASP/JES, when SYSIN and SYSOUT were plain old data sets and attributes, particularly SPACE, were tied to SYSOUT class and probably wrong. >> I didn't know that. Should I have RTFM? >> >> Is SDB aware of that? >> >> If BSAM, is this offset by more calls to WRITE/READ? >> >> BLKSIZE is incompatible with DD */DATA, perhaps because >> the programmer is expected to use F/V rather than FB/VB -- gil -- For IBM-MAIN subscribe / signoff / archive access instructions, send email to lists...@listserv.ua.edu with the message: INFO IBM-MAIN
