Control blocks

The control blocks associated with the EXEC interface are as follows:

EXEC interface block (EIB) (DSECT name: DFHEIBLK).
Each task in a command-level environment has a control block called the EXEC interface block (EIB) associated with it. The EIB is used for direct communication between command-level programs and CICS®.

The EIB contains information that is useful during the execution of an application program, such as the transaction identifier, the time and date (initially when the task is started, and subsequently, if updated by the application program), and the cursor position on a display device. The EIB also contains information that is helpful when a dump is being used to debug a program. DFHEIBLK defines the layout of an EIB, and is included automatically in the application program, giving access to all of the fields in the EIB by name.

A further EIB, known as the "system" EIB, exists for each task. The system EIB has the same format as the "user" (or "application") EIB. It is intended for use mainly by CICS system code. In general, application programs have addressability to the user EIB only, which is a copy taken of the system EIB at appropriate times. However, any service programs translated with the SYSEIB option have addressability to the system EIB also, so that they can issue EXEC CICS commands without causing the user EIB to be updated. (See the CICS Application Programming Guide for further information about the SYSEIB translator option.)

Figure 43 shows the format of an EIB.

EXEC interface communication area (DSECT name: DFHEICDS).
The EXEC interface communication area describes the storage that is used to pass the COMMAREA from one command-level transaction to another using an EXEC CICS RETURN command with the TRANSID, COMMAREA, and LENGTH options.

Figure 44 shows the format of the EXEC interface communication area.

Figure 44. EXEC interface communication area (EIC)
 This is a technical drawing showing the structure of the EXEC interface communication area (EIC).
Note:
EIC_SUBPOOL is a flag indicating the storage subpool used by the COMMAREA.
EXEC interface storage (EIS) (DSECT name: DFHEISDS).
The EXEC interface storage is used by DFHEIP as the interface between the application program and CICS control blocks. It contains a system area used by DFHEIP only. EIS is storage acquired by the DFHAPXM module (part of the transaction manager), along with other task-lifetime storage such as the TCA and both system and user EIBs. There is one EIS per transaction (not per program), and it is addressed by TCAEISA in the TCA. (See Figure 45.)

See the CICS Data Areas manual for a detailed description of these control blocks.

[[ Contents Previous Page | Next Page Index ]]