In CICS file control, which EXEC CICS READ command options would you use to read a VSAM KSDS record whose key begins with the prefix F using a generic key?

Introduction / Context:
CICS file control allows applications to read VSAM KSDS records not only by full key, but also by generic key, where only a prefix of the key is specified. This is useful when keys share a common starting pattern and the program needs to read the first record that matches that prefix. Understanding how to code the READ command with GENERIC and LENGTH options is important in such scenarios.

Given Data / Assumptions:

• The file is a VSAM KSDS defined to CICS with an associated FILE name.
• Keys have a defined length, and the program knows the prefix value F and the number of bytes in that prefix.
• The program wants to read the first record whose key begins with the prefix F, not necessarily an exact full key match.
• CICS supports GENERIC and LENGTH options on READ for generic key processing.

Concept / Approach:
To perform a generic key read, the application places the desired key prefix into a key area, sets LENGTH to the length of that prefix, and specifies GENERIC on the EXEC CICS READ command. CICS then interprets the key as generic, searching for the first record whose key begins with the specified prefix. The FILE and INTO options identify which file to access and where to place the record, while KEY indicates the address of the key area. This approach is different from using STARTBR for browsing or from using full key reads, which require the entire key value.

Step-by-Step Solution:
Step 1: Define a key area in the program and populate it with the prefix value F followed by any required padding. Step 2: Determine the number of bytes that make up the meaningful prefix and set a length field to that value. Step 3: Issue EXEC CICS READ FILE with INTO specifying the record buffer, KEY specifying the key area, GENERIC specified, and LENGTH specifying the prefix length. Step 4: Allow CICS to return the first record whose key begins with the prefix F into the INTO buffer for processing.

Verification / Alternative check:
CICS file control documentation describes generic key processing and shows syntax including KEY, GENERIC, and LENGTH. Examples illustrate reading the first record that matches a prefix rather than a complete key. They do not suggest using UPDATE alone or unrelated commands such as XCTL to fetch records. This confirms that a READ command with FILE, INTO, KEY, GENERIC, and LENGTH is the correct pattern for reading a record whose key begins with a specific prefix.

Why Other Options Are Wrong:
Option B is wrong because UPDATE relates to changing records and does not replace GENERIC or LENGTH for prefix handling. Option C incorrectly combines STARTBR and ENQ without specifying any key logic. Option D misuses WRITE, which creates or updates records rather than reading them. Option E incorrectly describes XCTL as a data access command when it is actually a control transfer command between programs.

Common Pitfalls:
A common mistake is forgetting to set LENGTH to the prefix length, which causes CICS to treat the key as a full key and miss the desired record. Another pitfall is not handling the NOTFND condition when no record with the given prefix exists. Developers sometimes also confuse generic key reads with browse operations, which use STARTBR and READNEXT instead. Understanding how to code EXEC CICS READ with GENERIC and LENGTH ensures correct and efficient processing of keyed VSAM data with common prefixes.

Final Answer:
Use EXEC CICS READ with FILE, INTO, KEY set to a key area containing prefix F, GENERIC specified, and LENGTH set to the prefix length so CICS reads the first record whose key begins with F