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 [email protected] with the message: INFO IBM-MAIN
