levels Definition/General, levels Definition/General

levels

Command levels Definition/General
Applicable release versions: AP
Category General (155)
Description describes level pushing.

Any command or program can be interrupted during execution by pressing the active "level pushing" key, (usually a <break> or <escape> key). When a command or program is interrupted, the system stops execution and saves all parameters so that execution can be resumed exactly where it was interrupted. When a process is interrupted at the normal system level, the system prompts with two colons. At this point the command or program is said to be "pushed one level".

Up to 16 levels may be "pushed". The number of colons in the prompt indicates the number of levels pushed. (The normal system level is considered level 1).

Pressing <return> at the "higher-level" TCL prompt returns to the previous level and continues execution of the process at that level.

The "end" command terminates the current process and returns control to the previous level.

"levels" are a function of the Pick virtual machine and should not be confused with spawning a child process (as would occur in the Unix engine). The current virtual task is suspended, a new virtual workspace is established, and "tcl" is activated as the current user.

In AP, each new level grabs a minimum of 4 frames (user control blocks). Since workspace is floating, new workspace is allocated as required. When a level wraps up and returns, all workspace associated with that level is returned to overflow.
Syntax
Options
Example
Purpose
Related tcl.esc-toggle
tcl.esc-data
tcl.esc-level
tcl.brk-debug
tcl.brk-level
tcl.level.pushing
prompt.chars.ap
system.debugger.:

levels

Command levels Definition/General
Applicable release versions: AP
Category General (155)
Description describes level pushing.

Any command or program can be interrupted during execution by pressing the active "level pushing" key, (usually a <break> or <escape> key). When a command or program is interrupted, the system stops execution and saves all parameters so that execution can be resumed exactly where it was interrupted. When a process is interrupted at the normal system level, the system prompts with two colons. At this point the command or program is said to be "pushed one level".

Up to 16 levels may be "pushed". The number of colons in the prompt indicates the number of levels pushed. (The normal system level is considered level 1).

Pressing <return> at the "higher-level" TCL prompt returns to the previous level and continues execution of the process at that level.

The "end" command terminates the current process and returns control to the previous level.

"levels" are a function of the Pick virtual machine and should not be confused with spawning a child process (as would occur in the Unix engine). The current virtual task is suspended, a new virtual workspace is established, and "tcl" is activated as the current user.

In AP, each new level grabs a minimum of 4 frames (user control blocks). Since workspace is floating, new workspace is allocated as required. When a level wraps up and returns, all workspace associated with that level is returned to overflow.
Syntax
Options
Example
Purpose
Related tcl.esc-toggle
tcl.esc-data
tcl.esc-level
tcl.brk-debug
tcl.brk-level
tcl.level.pushing
prompt.chars.ap
system.debugger.: