To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) Begins the subparameters of the DCB - This option is correct. The DD DCB keyword is used to begin the subparameters of the DCB (Data Control Block). The DCB contains various parameters that define the attributes of a dataset, such as the record format, block size, and organization.

Option B) Begins the DASD control block - This option is incorrect. The DD DCB keyword is not used to begin the DASD (Direct Access Storage Device) control block. The DASD control block is used to define the characteristics of a disk drive or storage device.

Option C) Marks the close of the DCB - This option is incorrect. The DD DCB keyword does not mark the close of the DCB. The closing of the DCB is typically indicated by the END or EOF (End of File) keyword.

Option D) Modifies the record type parameters - This option is incorrect. The DD DCB keyword does not modify the record type parameters. The record type parameters, such as RECFM (Record Format) and LRECL (Logical Record Length), are specified separately in the DCB.

The correct answer is A) Begins the subparameters of the DCB. This option is correct because the DD DCB keyword is used to indicate the start of the subparameters that define the attributes of a dataset in the DCB.

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To answer this question, you need to understand the concept of variable shielding in subroutines.

Option A) One can not shield variables in a subroutine from the main EXEC, only from other subroutines. This option is incorrect because it suggests that variables in a subroutine cannot be shielded from the main EXEC. In reality, it is possible to shield variables from both the main EXEC and other subroutines.

Option B) One can shield the variables by using the clause: CALL SUBROUT1 PROCEDURE This option is incorrect because the clause "CALL SUBROUT1 PROCEDURE" does not shield variables. It is used to call a subroutine, not to shield variables.

Option C) One can shield the variables by defining the start clause of a subroutine: SUBROUT1: PROCEDURE This option is correct because the start clause of a subroutine can be used to shield variables. By defining the subroutine with a start clause such as "SUBROUT1: PROCEDURE", the variables within that subroutine are shielded from the main EXEC and other subroutines.

Option D) One can shield the variables by defining the start clause of a subroutine: SUBROUT1: SHIELDED This option is incorrect because the keyword "SHIELDED" is not used to shield variables in a subroutine. The correct keyword to use is "PROCEDURE".

Therefore, the correct answer is Option C) One can shield the variables by defining the start clause of a subroutine: SUBROUT1: PROCEDURE. This option is correct because it accurately describes the method of shielding variables in a subroutine from the main EXEC.

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To answer this question, let's go through each option to understand why it is correct or incorrect:

Option A) Marks a deleted DD statement - This option is incorrect. The purpose of the DD DUMMY statement is not to mark a deleted DD statement.

Option B) Begins an interpreted command stream - This option is incorrect. The purpose of the DD DUMMY statement is not to begin an interpreted command stream.

Option C) Specifies no space allocation & no disposition processing - This option is correct. The DD DUMMY statement is used to specify that no space allocation should be performed and no disposition processing should be done for the DD statement.

Option D) Suppress command processing - This option is incorrect. The purpose of the DD DUMMY statement is not to suppress command processing.

The correct answer is C) Specifies no space allocation & no disposition processing. This option is correct because the DD DUMMY statement is used to specify that no space allocation should be performed and no disposition processing should be done for the DD statement.

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To answer this question, you need to understand the concept of JCL (Job Control Language) statements. JCL is a scripting language used on IBM mainframe operating systems to control batch processing.

The fields in JCL statements that contain specific values designed to direct and control the execution of the statement are called "Parameters."

Option A) Linkage Variables - This option is incorrect because linkage variables are used in programming languages like COBOL to pass data between different programs or modules. They are not specific to JCL statements.

Option B) Parameters - This option is correct because parameters are the fields in JCL statements that contain specific values to direct and control the execution of the statement.

Option C) Control Libraries - This option is incorrect because control libraries are used in JCL statements to specify the location of system control programs or procedures. They are not the fields that direct and control the execution of the statement.

Option D) Includes - This option is incorrect because includes are used in JCL statements to include external files or libraries into the JCL. They are not the fields that direct and control the execution of the statement.

The correct answer is B) Parameters. This option is correct because parameters are the fields in JCL statements that contain specific values to direct and control the execution of the statement.

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To answer this question, you need to understand the command used to activate the interactive trace in REXX.

Option A) TRACE R - This option is incorrect because the TRACE R command does not activate the interactive trace. Instead, it activates the trace for the execution of a REXX program.

Option B) TRACE ?R - This option is correct because the TRACE ?R command activates the interactive trace. The ? symbol is used to indicate an interactive trace in REXX.

Option C) TRACE IR - This option is incorrect because the TRACE IR command does not activate the interactive trace. Instead, it activates the trace for the execution of a REXX program.

Option D) INTTRACE R - This option is incorrect because the INTTRACE R command does not activate the interactive trace. Instead, it activates the internal trace for the execution of a REXX program.

The correct answer is B) TRACE ?R. This option is correct because it activates the interactive trace in REXX.

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