IAMDRCC examples

The following are the examples of the Dynamic Reorganization program IAMDRCC. As described the IAMDRCC-Control-statements, the IAMDRCC program facilitates the reorganization of an IAM file that is opened for update under a CICS region IAMSRORG functions. The actual example JCL is contained in the .IAMSAMP data set that is distributed as part of the IAM product. The examples are found in the member name that matches the corresponding example identifier. For example, the first example which is called EX4304A will be in member EX4304A of the JCL library. This is example JCL only, and must change as necessary for the system that you are using the example JCL on.

Example EX4304A

The job below performs the following functions:

1. Establish an EXCI connection to the CICS region CICSBPRD to facilitate a dynamic reorganization while the data set is open.
2. The data set to be reorganized is IAMCICSV.IAQA.LOCAL.IVTK1 which is dynamically allocated by IAMDRCC.
3. A reorganized copy of the IAMCICSV.IAQA.LOCAL.IVTK1 data set will be created into the data set IAMCICSV.IAQA.LOCAL.IVTK1X. If necessary that data set will be defined using the attributes of the original data set.
4. When the copy has completed, then the original data set IAMCICSV.IAQA.LOCAL.IVTK1 will be closed to CICS, and the following functions performed:
   • Records that were updated while the copy process was being performed will be updated in the new reorganized data set
     IAMCICSV.IAQA.LOCAL.IVTK1X.
   • The original data set IAMCICSV.IAQA.LOCAL.IVTK1 will be renamed to IAMCICSV.IAQA.LOCAL.IVTK1.Dddmmyy to serve as a backup data set.
   • The reorganized copy of that data set will then be renamed to
     IAMCICSV.IAQA.LOCAL.IVTK1.
   • The data set IAMCICSV.IAQA.LOCAL.IVTK1 will then be reopened under CICS.

Example EX4304A of Dynamic Reorganization

The original data set is specified by the FROM keyword, the data set to contain the reorganized copy is specified by the TO keyword. Based on the SAVESFX value of DDMMYY, the original data set will be renamed to IAMCICSV.IAQA.LOCAL.IVTK1.Dddmmyy. All functions are automatically performed without any operator or user interaction.

Example output

Shown on the following page is an example of the printed output produced by IAMDRCC for the reorganization of an IAM KSDS data set. The format is similar to a log type listing where there is a data and time stamp in the left side, generally followed by the name of the program that is producing the message. With this format it is easy to follow through on the flow of the reorganization process.

1. 
   
   1. The output starts with an echo of the provided REORG statement. This is followed by a box th a summary of the name of the data set to be reorganized, followed by the name of the new reorganized copy, and the name of the CICS region.
   2. The next set of messages regard the establishment of communication with the specified CICS region. The process will verify that the CICS region does have the specified IAM file open, that the IAM file has data in the extended areas of the file so a reorganization will be useful, and notification of what data sets will need to be closed to complete the reorganization. As shown in this example, it is just the target data set. For data sets with an alternate index, there will be multiple data sets as shown in the subsequent example. We also see confirmation that the tracking of changes has been activated.
   3. This section shows the messages from the IAMSRORG program that is used to create the reorganized copy of the input data set. If the output data set did not previously exist, there will also be the output from IDCAMS for the DEFINE Cluster to define and allocate the output data set. The messages include the counts of records read from the input file and written to the output file.
   4. Upon completion of creating the reorganized copy of the input data set. the next step is to perform the Phase 1 updates. The process essentially does a syncpoint on the tracking table to indicate what will be the starting point for the Phase 2 updates. It then proceeds with updating the reorganized copy with all of the inserts, updates, and deletes that were done during the actual copy process. The original data set remains open for full update use during the Phase 1 updating of the new reorganized copy.
   5. The next section starts at the completion of the Phase 1 update process. It is now time for the data set to be closed to CICS. Presuming that the automatic close process is used, we see messages indicating that process. This marks the time at which the data set is unavailable to CICS. The time stamp from the message indicating issuing the request to close the data set can be used to mark the starting time of the data set not being available. In this case that time stamp was 16:29:18:9402. Once IAMDRCC receives confirmation from CICS that the data set is closed, it will now perform the Phase 2 updates to the new file, which are all the updates that were done since the beginning of Phase 1 shown in the prior step. Phase 2 performs the various updates, and completes with a summary of the updates that were performed by Phase 2.
   6. Upon completion of Phase 2 updates, IAMDRCC is now ready to do the renames to swap the new data set to the original data set name and resume processing. The messages show the data set renames being done via IDCAMS ALTER commands. With successful completion of the renames, IAMDRCC now will request to CICS to reopen the IAM data set. A key message here is the completion message of the request to open the data set indicating that the request was successful. The time stamp on this message can be used to mark the time of data set availability which in this case was 16:29:21:4931. The data set in this case was unavailable for 2.5529 seconds. IAMDRCC then notifies CICS that the process is complete so it can terminate and then IAMDRCC disconnects from CICS.

Sample of Dynamic Reorg Output

Example EX4304B

This is an example of using IAMDRCC to perform multiple concurrent reorganizations. In this example notice in the JCL example below that the EXEC card has the parameter of PARM=’SUBTASKS=3’ which specifies that IAMDRCC will use three concurrently executing subtasks to perform three independent IAM data set reorganizations. In the SYSIN control cards are three REORG for different data sets that will be reorganized by the three subtasks. Rather than intermixing the output, each subtask keeps in virtual storage all of the messages that relate to the reorg it is performing. When the reorg process completes, it will then write all of the associated messages to the SYSPRIINT card with the full details of the processing. The SYSPRINT example above shows what is produced by one subtask, each additional task that performs a REORG will produce a similar report. A shorter printed output of each REORG that was processed is written out to the DRSUMM DD card if it is provided.

Notice that the SYSIN statements include the BEGIN statement as the first statement and the END statement as the last statement. These statements request the Enabling of and Disabling of the High Activity Toleration (HAT) CICS GLUE Exits to ensure that all CICS Reads and Writes complete successfully across the necessary short duration auto file close, rename, and open.

As each subtask completes a REORG, if will pick up the next REORG if there are any to be processed. Upon completion of all of the REORG statements, IAMDRCC processing is terminated.

EX4304B JCL

The following example is a sample EX4304B JCL:

EX4304B DRCMD example listing

The following examples is the summary output for the three reorganizations. It contains the relevant control card statement, identification of the data sets involved in the REORG process, and return code from the REORG process. The complete processing information is on SYSPRINT, and can be found by using the link provided below.

EX4304B example of DRCMD output

Copy example EX4304E

The following example uses IAMDRCC to obtain a copy of a data set that is open for update under CICS. The copy can be used as a non-fuzzy backup or it can be used for pushing the data to other spots in your IT organization such as to a distributed platform.

EX4304E JCL Example