1.  Q: Wouldn't you need a huge memory buffers to keep the sampling results?
     A: No. ICPU uses a unique technique where the load module is logically divided into equal size pieces, called slices, and when a sample event occurs, ICPU figures out what slice the PSW is pointing at, and updates the slice and the program counters. These counters exist only for the active programs and slices and therefore the buffer requirements are minimal. .

2.    Q: What information does ICPU give me that the other performance monitors do NOT give me?
        A: The popular performance monitors concentrate on transaction response time and try to point out the reasons for any unacceptable response time. If a transaction is using too much CPU, these monitors would not tell you which of the programs executed during the transaction life is responsible for it, nor will they be able to tell you which of the program instructions are using the most CPU.

3.    Q: What information does ICPU give me that other sampling products do NOT give me?
        A: ICPU is the only real time sampling product which can run unlimited, discovering and reporting any problems as they occur, so you can take a corrective action immediately. All other sampling products are postmortem tools which are used only after a problem occurs and their heavy overhead limits their usability and functionality. 

4.    Q: Is there any concern with overhead at high transaction rates, which can be hundreds of transactions per second?
        A: No. Due to its unique architecture, ICPU remains at a constant minimal overhead regardless of the transaction rate at a given time.

5.    Q: Does ICPU use any hooks or SVC or non-standard mechanism to gather the information it needs?
        A: No, ICPU uses only standard CICS and MVS commands, macros and functionality.

6.    Q: What do I do when the ICPUCICS file is full and I need to enlarge it, do I lose any inspections?
        A: ICPU files are standard VSAM KSDS files. To increase the size of the file, you have to define a new file with a larger size, REPRO the old file to the new one and start using the new one.  
 
7.    Q: Can I watch online the inspection results?
        A: ICPU is a real time tool and whenever you display the sampling results you get the updated sampling results up to the last sample taken.

8.    Q: Can more than one user use ICPU at the same time? What is the expected impact?
        A: Any number of users can use ICPU at the same time without affecting the overhead.
 
9.    Q: Can I run ICPU in the production environment? What is the expected impact?
        A: Yes, with no problems. ICPU will have a minimal impact on your production systems because of its low overhead and the use of standard coding and interfaces.

10. Q: What is OSRV?
        A: OSRV is the CPU used when an instruction is executed by a service routine, other than CICS itself. For example, the COBOL INSPECT statement, or the COMPUTE statement involving floating point fields which is processed by the IGZCFPC Language Environment routine.

11.    Q: How long does it take to install ICPU?
        A:  Less than an hour. You have to load the Load and Sample libraries, update the CICS resource definitions, and define and initialize the ICPU files.
For CICSTS 3.2 and above you can use the dynamic library feature to define ICPU load library, otherwise you need to concatenate the load library to the DFHRPL.
 
12. Q: How do you deliver fixes to ICPU?
        A: Usually, you'll get a new load library containing the fix, which will totaly replace the current library. 

13. Q: Which versions of CICS and z/OS are supported by ICPU?
        A:  ICPU supports CICS/MVS 4.1 and CICSTS 1.1 up to CICSTS 5.3, and up to z/Os 2.2. Support for new OS and CICS releases are added, as they are made available to the developer community.

14. Q: Do you support sampling of THREADSAFE programs?
        A: Yes, threadsafe is supported and the results are reported for any program, executed on any EXEC capable TCB.

15. Q: What languages does ICPU support?
        A: At sample time, ICPU looks at the load module, and therefore ICPU supports any language supported by CICS. In addition, the Source Listing feature can be used to see the program source code of the high CPU usage slices for COBOL programs. 

16. Q: Is it possible to get ICPU for a trial?
        A:   Yes, when you install ICPU a trial password is generated automatically, which lets you use ICPU free for one month. During this trial period the number of inspections is limited to 9, the run time is 15 minutes and you will be able to see the high CPU usage programs, but the offsets will be displayed only for ICPU demo programs.

17. Q: If I want to turn on ICPU every day, starting from CICS start up until CICS shut down, do I have to logon into CICS and do it manually?
        A:   No. ICPU has two features, Line command and Generic Inspection Ids which can be used to run ICPU unattended. All you have to do is run the ICPU transaction from a card reader/line printer terminal. A line command such as: "ICPU S,A+" entered on a CRLP terminal will start inspection every time that CICS comes up, creating a sequence of Inspection Ids, starting from A0000001, and going up.

18. Q: If CICS crashes, do I loose the sampling results?
        A: No. ICPU has a checkpoint feature that is specified through the Check Point Interval during customization. ICPU will be invoked periodically according to this interval and record the sampling results onto the ICPUCICS file.
 
19. Q: How do you support CICSPLEX, do you need a separate ICPUCICS file for each CICS?
        A:  No. The ICPU password is based on bytes 3-6 of the CPU serial number.  As a result you can use the same password on any CICS region running under the same machine, and the multi-password feature of ICPU allows you to use the same ICPUCICS file on up to 4 machines. The ICPUCICS file can be shared between several CICS regions using CICS function shipping or VSAM RLS processing.

 
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