TCB

Task Control Block

This numeric function returns the status of certain program execution values that change during processing of a task. These values relate to error and escape processing and are continuously updated by the appropriate directives and system processes.

Syntax

TCB (numeric-value [,ERR=line-ref|,ERC=error-code])

numeric-value: is any integer in the range of 0 to 9 or 13.
line-ref: is the program line number or label to branch to if an error is produced by this function.
error-code: is a programmer-defined error code. Valid values are positive or negative whole numbers.

Remarks

This function returns the following values:

TCB (): returns 0
TCB (1): returns the number of available entries for Public Programs
TCB (2): returns the channel of the last error except channel 0
TCB (3): returns the last operating system error code
TCB (4): returns the current statement number
TCB (5): returns the number of the statement that last caused an error
TCB (6): returns the statement that SETESC is set to
TCB (7): returns the statement that SETERR is set to
TCB (8): returns the shell exit code from the last SYSTEM directive
TCB (9): returns the shell termination status
TCB: (13) returns the current public program level. The value is the actual number of public programs in the stack. While in the main program, this value is 0.
TCB(29): returns the journaling trace mode value. This value is used for the debugging of journaling problems.
TCB(30): returns the variable name entry mode:

0 LONGVAR is enabled ( the default )

1 SHORTVAR is enabled

TCB(40): returns the sort number that generated the error 107
TCB(41): returns the sort field that generated the error 107.
TCB(42): returns a value that represents the reason for the error 107:

-1 No sorts defined or the specified sort is not defined

-2 Invalid sort field

-3 Error during the numeric conversion of the sort field. See TCB(43) for the basic error code

-4 Error during I/O. See TCB(43) for the basic error code

TCB(43): returns the basic error code that generated the error 107. See TCB(42).

Examples

LET X = TCB (6)

If X is assigned the value 5678, the statement that the SETESC directive is set to is 05678.

LET ERROR_LINE = TCB(5), ERROR_CODE = ERR

provides information to the programmer about what error most recently occurred and at what line in the program.

TCB

Syntax

Remarks

Examples

See also