In CICS system administration, which CICS service transaction is commonly used to inquire on and modify CICS control tables and resources, and which one has the highest priority?

Introduction / Context:
CICS regions maintain many internal control tables and resource definitions that affect programs, files, terminals, and transactions. System programmers and administrators use special service transactions to inquire on and sometimes modify these definitions while the region is running. One of the most important of these is the CEMT master terminal transaction, which is designed for high priority administrative use. This question asks you to identify that transaction and its role.

Given Data / Assumptions:

• Control tables and resource definitions in CICS govern how programs, tasks, and terminals behave.
• Administrators need online tools to inquire on and change certain attributes without stopping the region.
• CICS provides a master terminal concept and associated transaction for system level control.
• The question focuses on the transaction that accesses control tables and has very high priority.

Concept / Approach:
CEMT is the master terminal transaction that allows authorized users to inquire on and alter the status of many CICS resources such as programs, transactions, files, and terminals. It can be used to enable, disable, or set new attributes for these resources, often by talking directly to internal control information. Because it affects the health and configuration of the region, CEMT typically runs with very high priority so that system level requests are not delayed behind ordinary application workload.

Step-by-Step Solution:
Step 1: Recognize that service transactions are different from normal application transactions and are used for administration. Step 2: Recall that CEMT is known as the master terminal transaction and is used for inquires and changes to resource status. Step 3: Understand that CEMT has higher priority because it controls resources that affect the whole region. Step 4: Choose the option that correctly identifies CEMT as the service transaction with high priority and access to control table information.

Verification / Alternative check:
CICS documentation lists CEMT as a master terminal transaction and shows commands like CEMT I PROGRAM or CEMT SET FILE that inquire on and modify resource definitions. It also describes the security considerations and emphasizes that CEMT requests should not be blocked by normal workload. Other transactions such as CESN are described as logon transactions, not as control table administrators. This confirms that the option naming CEMT is correct.

Why Other Options Are Wrong:
Option B is wrong because CESN is used for user signon and does not define programs or act as the highest priority transaction in the system. Option C mislabels CEDA, which is a resource definition transaction, not a simple signon tool, and the option still does not mention high priority control table access correctly. Option D incorrectly claims that CEMT is for end users and cannot be used by administrators, which is the opposite of reality. Option E is incorrect because CICS allows many updates to definitions without IPL of the mainframe, through service transactions and configuration changes.

Common Pitfalls:
A common pitfall is allowing too many users to access CEMT without proper security, which can lead to accidental changes in critical resources. Another issue is confusing CEMT with other transactions such as CEDA and CECI, which also work with definitions and commands but have different roles. Administrators should use CEMT carefully, follow change control procedures, and ensure that proper auditing is in place. Understanding the purpose and priority of CEMT helps maintain a stable and secure CICS environment.

Final Answer:
The CEMT master terminal transaction is used to inquire on and modify many CICS control tables and resource definitions online and it runs with very high priority compared to normal application transactions