Mainframe, MVS and zOS Discussion

1. When one needs to position the key to the last record in the VSAM data-set, while using a VSAM KSDS data-set in CICS - move HIGH-VALUES to the key field (RIDFLD) and then execute a STARTBTR. This will position the control on the last record of the data-set and a subsequent READNEXT or READPREV can be executed.

2. You're using STARTBR and want to update a particular VSAM record? Following these steps will get you going:

1. End the browse on the desired record by issuing a READ UPDATE.
2. REWRITE after changing the the contents.
3. Issue another STARTBR.
4. Issue READNEXT twice*.

* - the first READNEXT will reread the same record

3. While testing, some time, while executing a CICS transaction, a transaction might hold the resources because it went in a loop. To terminate this event, use the following command:
With that, all the transactions, running, will get listed. Go to the transaction that is looping and issue FP command against it. This will forcefully purge the transaction and frees the buffer space.

4. One can use the CETR transaction to to see if you have any unnecessary traces running. Once determined, remove any trace you don't need.

In application programming, it's advisable to use DFHRESP function to test the EIB return codes instead of using HANDLE conditions.

5.You can set the program enable or disable by providing
The same can be done for Transaction as well

6.You can call a CICS program from batch through. EXCI

7. Online Job Submissions
Sometimes an online application may need to trigger and run a batch job for processing a large workload, asynchronously. EXEC CICS SPOOLOPEN and EXEC CICS SPOOLWRITE allow you to write information to a SYSOUT dataset. If you write JCL statements to a SYSOUT dataset using SPOOLWRITE and as input to INTRDR, it would submit the JCL.

8. CICS Dump Analysis -
If you don't have a dump analysis tool like Dump Master at your shop and you like to find out the instruction where the program failed, here's a CICS transaction dump cookbook, which lays down steps on how to find the COBOL statement, WS- or LS-Variable state from the dump.

ftp://ftp.software.ibm.com/software/my/ ... -Dumps.pdf
Interesting - I learnt that in core memory, addressing each 4K block needs a Base Locator. So, you'd have a BLW0, BLW1, BLW2 for each 4k chunk. The BLLs/BLWs addresses can be found in the TGT memory map at the end of the compile listing. And the TGT's address can be found in GPR09(Registers at the time of Interrupt.