Customizing the REXX EXEC

About this task

You start the CICS BAC ISPF administration interface by invoking by a REXX EXEC, which is supplied as member CBKRCBAC in the SCBKEXEC data set. Before you attempt to use the CICS BAC administration interface, first customize the REXX EXEC. When you customize the EXEC, it is important that you apply your customization changes to a copy of CBKRCBAC, and do not change the supplied CBKRCBAC member in SCBKEXEC. If you modify the supplied version of CBKRCBAC in data set SCBKEXEC, your changes could be overwritten by any future maintenance to the CICS BAC-supplied member. You can use one of the following methods to avoid modifying the original:
  • Create a copy of CBKRCBAC with a new name in the SCBKEXEC data set, choosing a name that suits your own naming standards, such as CBKRCUST
  • Create a copy of CBKRCBAC in a different REXX EXEC data set that you plan to use for the ISPF administration interface, and keep the name of the copy as CBKRCBAC

Where relevant, the discussion in this manual is based on the first of these methods using the EXEC name CBKRCUST and the data set name SCBKEXEC.

When you have created a copy of CBKRCBAC, customize it to suit your installation standards. Some of the customization is required, and some is optional. (Note that character strings need to be enclosed in double quotation marks as shown in the parameter descriptions.) The required changes are to REXX EXEC parameters that specify data set names, and also the mirror transaction identifier, described as follows:

CBKCMIR = “CSMI”|“tranid
Specifies the name of the CICS® mirror transaction to be specified on EXCI requests issued by CICS BAC ISPF administration interface. When the EXCI request is executed in the target CICS region, it runs under this transaction ID as an MRO mirror transaction.
CSMI
This is the normal CICS EXCI default mirror transaction ID.
transid
Specifies the 4-character name that you want CICS to use as the name of the MRO mirror transaction when it executes the EXCI requests it receives from CICS BAC ISPF administration interface. To avoid confusion with other mirror transactions that might be running in your CICS regions, you might want to choose a unique ID to identify CICS BAC ISPF administration interface mirror transactions. Define the appropriate transaction ID in the CICS region for a CICS mirror transaction, ensuring the following:
  • The program associated with the transaction ID must be DFHMIRS
  • The profile for the transaction ID must be DFHCICSA.
You might consider using the CICS-supplied CSMI transaction definition as a basis for this transaction ID.
CBKLLIB=“&hlq.SCBKLOAD”
CBKEXEC=“&hlq.SCBKEXEC”
CBKMLIB=“&hlq.SCBKMENU”
CBKPLIB=“&hlq.SCBKPENU”
CBKTLIB=“&hlq.SCBKTENU”
Specify your own high-level qualifiers that you chose for these five ISPF administration interface data sets when you installed them. In CBKRCBAC, the data set names are defined on their respective parameters with the prefix &hlq. Substitute the actual high-level qualifier for the string &hlq. The five parameters, and their corresponding data sets, are as follows:
CBKLLIB
Specifies SCBKLOAD, the CICS BAC module load library
CBKEXEC
Specifies SCBKEXEC, the CICS BAC REXX EXEC library
CBKMLIB
Specifies SCBKMENU, the CICS BAC ISPF administration interface English messages data set
CBKPLIB
Specifies SCBKPENU, the CICS BAC ISPF administration interface panels data set
CBKTLIB
Specifies SCBKTENU, the CICS BAC ISPF administration interface English table data set containing the default PF key settings.
CBKSUMLQ=“middle_qualifier
Specifies the middle qualifier of the data set that the ISPF administration interface uses to save information about each user of the interface. This is referred to as the TSO user's CICS BAC ISPF table. The REXX EXEC allocates the data set with a name in the form TSOuserid.cbksumlq.CBKTABL, where TSOuserid is the TSO user ID, and cbksumlq is the middle qualifier. The first time you start the ISPF administration interface it creates the CICS BAC TSO user data set automatically for you, and thereafter allocates the data set each time you start the interface.
middle_qualifier
Specifies the middle qualifier of the data set that the ISPF administration interface maintains for each TSO user of the interface. The high-level qualifier is the TSO user ID and the low-level name is CBKTABL. The ISPF administration interface use this TSO user's CICS BAC ISPF table to save your data when you select various options from the primary menu. See Specifying the control file table data set and Selecting a target CICS region.
The remaining parameters in the EXEC that you can tailor for your own needs are all optional.
CBKCFTDS=“table_dataset_name
Specifies a default control file table data set name. If you specify this parameter, the ISPF administration interface uses this table data set name whenever a user starts the ISPF administration interface for the first time; that is, when the user data set specified by the CBKSUMLQ does not exist. The default control file table data set name specified by CBKCFTDS is stored in your TSO user's CICS BAC ISPF table as an initial value, and is the same for all new user's of the CICS BAC ISPF interface.

When the CICS BAC REXX EXEC starts, it checks to see if the TSO user's CICS BAC ISPF table (as specified using the CBKSUMLQ parameter) already exists, and if it does, the TSO user is not a new user and the ISPF administration interface ignores the CBKCFTDS parameter.

If the TSO user's CICS BAC ISPF table does not exist, the ISPF interface checks to see if CBKCFTDS specifies a data set name (that is, not a null value). If CBKCFTDS specifies a valid data set name, it is entered in the TSO user's CICS BAC ISPF table as the name of the control file table data set name.

Using this parameter removes the need for new users of the interface to specify their control file table data set name using option 3 on the Primary Option Menu. However, although the data set is specified by the CBKCFTDS parameter, it is not selected for the ISPF session and you still have to select the data set using option 2 on the Primary Option Menu.

Note: If you specify the CBKCFTDS in your CICS BAC REXX EXEC parameters, it is used for all new users of the CICS BAC ISPF administration interface and thus can be used only when the control file table data set name specified is common to all users of the interface.
CBKCFTCO
Specifies a default control file table data set comment about the data set specified on CBKCFTDS. This is used only when you also specify the CBKCFTDS parameter.
CBKSMAXD=12|number
Specifies the maximum number of 4KB pages the ISPF interface is to allocate as a buffer for downloading data from the target CICS region. You can specify a number of pages in the range 1 through 999; the default is 12.
Note: Note that a command fails if the allocated buffer is too small for the command.
CBKSBRWE=4096||number
Specifies the maximum number of browse entries the ISPF interface is to allow to be downloaded for any request. This affects the list of resources for a selected region, as well as prompt lists for resource types. You can specify a number in the range 1 to 4096; the default is 4096.
CBKSLPRM=“N”|“Y”
Specifies that the ISPF administration interface is automatically to use the MV logical parmlib concatenation when looking for the control file table CBKCFTBL.
N
On initial startup do not look for CBKCFTBL in the MVS parmlib concatenation
Y
On initial startup, automatically look for CBKCFTBL in the MVS parmlib concatenation.

All the required and optional customization fields are fully commented in the CBKRCBAC REXX EXEC.