On 5/10/2024 3:08 am, Raphael Dal Pos via groups.io wrote:
Use command : DD CLEAR,DSN=ALL
If I had to guess, I'd say the DUMPDS (or DD for short) command came in with MVS/XA.
Also with MVS/XA blocking for SYS1.PARMLIB (definitely) and SYS1.DUMPxx (probably) were also allowed.
These days dump data sets have RECFM=FBS, and the LRECL is not longer than MVS 3.8's 4104.
Most records are used to contain the image of a virtual storage page and of course some header information with virtual storage address and ASID data is also required.
64-bit addressing is one obvious cause for the LRECL getting a bit longer - maybe it is 4160 these days.
Dumps from MVS/XA could be much bigger so the trend went away from printed dumps to enhancing IPCS.
The AMDPRDMP service aid was done away with and to reduce IPCS I/O, blocking was supported.
SYS1.DUMP data sets are sequential data sets with fixed-length records.
When a dump is stored into them, the VTOC entry is not updated, so they still appear to be empty to most utilities even when they contain a dump.
To empty them for reuse, they need to be initialized with an EOF marker or an empty first track.
Most sites added their own started task to SYS1.PROCLIB which used IEBGENER to copy in a DUMMY data set to the SYS1.DUMP data set (with the suffix set by command/JCL symbol).
From the console you can issue
DISPLAY DUMP
(or D D for short) to display dump data set status.
You might prefer to issue
D D,L=Z
to avoid the need for a subsequent K E,D if using a 3270 console.
D D defaults to D D,S (or DISPLAY DUMP,STATUS for long).
D D,O displays dump settings.
On TSO, IPCS supplies the SYSDSCAN TSO command. For example, on my system the TSO command
sysdscan 00:02
yields the following output:
SYS1.DUMP00 IS EMPTY
DATA SET SYS1.DUMP01 NOT IN CATALOG OR CATALOG CAN NOT BE ACCESSED
DATA SET SYS1.DUMP02 NOT IN CATALOG OR CATALOG CAN NOT BE ACCESSED
If SYS1.DUMP00 contained a dump, it would have displayed the dump title.
If I edit SYS1.DUMP00 to add a record record with some text and then issue
SYSDSCAN 00
I get
NO TITLE RECORD FOUND FOR SYS1.DUMP00
An easy way to empty a SYS1.DUMP data set that contains a dump is by using the PDS command.? For example
pds 'sys1.dump00' fix reset
will empty SYS1.DUMP00.? (Yes, the PDS command can process sequential data sets too!)
On z/OS dump data sets are not pre-defined but are allocated (created) dynamically.
When I get an SVC or SYSMDUMP dump from a customer to look at, the first thing I do is browse it and scroll right until I see the z/OS release indicator (in text) in the first record so I know which IPCS environment to use so that the z/OS release of IPCS matches the z/OS release of the customer's system.? I am hardly an IPCS expert (wish I was better), but I can usually find what I need in the dump.? I have not tried IPCS on MVS 3.8 at all.? For z/OS, IPCS is an ISPF application (although it still work from READY I presume), but it's a bit more primitive on MVS 3.8 I'll bet.
Anyway, that's my dump data set trivia...
Cheers,
Greg
