CICS® can access DL/I databases in an IMS Database Manager/Transaction Manager (IMS DM/TM) system by using the CICS-DBCTL interface or by using remote DL/I.
Using DBCTL
DBCTL satisfies DL/I requests issued from the CICS system
with the CICS-DBCTL interface. This means that you can have
access to DL/I databases controlled by IMS
DM/TM without needing to use IMS data sharing,
if CICS and IMS DM/TM are in the same z/OS® image.
Using remote DL/I
Remote DL/I is done with CICS function shipping a DL/I
request to another CICS system, in which the DL/I support can
be remote DL/I or DBCTL. For more information about function shipping, see CICS function shipping. For information about adding remote DL/I support, see Defining DL/I support.
Note:
Although these methods to access DL/I databases can coexist, a
program specification block (PSB) can only contain databases that
are controlled by one of the methods.
CICS Transaction Server
does not support local DL/I.
Figure 1 illustrates the DL/I request. Figure 1. DL/I
request handling within CICS
Request #1 is a DBCTL request from CICSA to DBCTLA for
a database controlled by DBCTLA. See CICS-DL/I router (DFHDLI)
for a description of request processing.
Requests #2a and #2b are two separate remote (function shipped) DL/I requests to databases
controlled by, or connected to, other CICS systems (which can
be in the same z/OS image or in different z/OS images). There are two ways of issuing such requests:
Request #2a from CICSA to CICSB for a database
controlled by CICSB.
Request #2b from CICSA to CICSB for a database
controlled by DBCTLB. The most likely reason for using request #2b is if
CICSA and CICSB are in different z/OS images.
IMS system service requests that CICS application programs can use
CICS application
programs can use the following IMS system service requests in addition to those related to data availability:
DEQ (in its command or call format) releases segments that were retrieved using the LOCKCLASS
keyword or the Q command code. LOCKCLASS and Q enable an application program to reserve segments for
its use.
LOG (in its command or call format) can be used to write a record from an application program to
the IMS log. You may
prefer to use this instead of EXEC CICS journal commands so that all your DBCTL
information is on the IMS log instead of the CICS log.
You can use the following tools and utilities to perform administration operations.
CICS-supplied transaction CDBC
You can connect to, and disconnect from, DBCTL using the CICS-supplied transaction CDBC. When you have connected to DBCTL by means of CDBC, you can
issue DL/I requests from your application programs. There is another CICS-supplied transaction, CDBI, which you can use to inquire on the status of the
connection to DBCTL from CICS. See Connecting to DBCTL: overview for information on using CDBC and
CDBI.
Online image copy utility
The online image copy utility is used to create an as-is copy of your database while it is being
updated. The copy can then be used for recovery purposes. This utility is used for HISAM, HDAM, and
HIDAM databases only.
Online change utility
In many installations, it is important for the online system to be is available to users for
most of the day. The online change utility enables you to update ACBLIBs, which contain PSBs and
data management blocks (DMBs), and security information belonging to full function databases,
without bringing down the system. For guidance information on this utility, see IMS administration in IMS product documentation and Database utilities in IMS product documentation.
The data entry database (DEDB) direct reorganization utility
The data entry database (DEDB) direct reorganization utility enables you to reorganize DEDBs
without taking them offline. For more information, see Access to data entry databases (DEDBs).
Terminology: The coordinator control subsystem (CCTL)
refers to the transaction management subsystem that communicates with DBCTL through the database
resource adapter (DRA). In a CICS-DBCTL environment, the CCTL
is CICS. The term
CCTL is used in a number of DBCTL operator commands and in the IMS manuals. CICS users of DBCTL should take the
term CCTL to mean a CICS system that is attached to IMS by means of DBCTL.
