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escape

Transfer Control to the Operating System Debugger

ABBREVIATION

es{cape}

FORMAT

escape

DESCRIPTION

The escape command transfers control from the SAS/C Debugger to TEST under TSO or to CP under CMS and lets you return to the program executing under the SAS/C Debugger at the place where you left it. You enter TEST or CP in the context of the program being debugged. You need to perform the following steps before you can use escape:

1. When you enter the debugger, press the attention key to transfer control to CP or TSO TEST.

2. Using commands for your operating system, request the breakpoint specified on entry to the SAS/C Debugger. This breakpoint is stated in the header you see when you call the SAS/C Debugger.

3. After you request this breakpoint (using commands for your operating system), reenter the SAS/C Debugger (also using commands for your operating system).

When you issue the escape command while executing your program under the SAS/C Debugger, you escape to TSO TEST or CP. The screen is refreshed after completion of execution of the escape command.

If you do not request the breakpoint for escape according to the instructions and try to use escape, nothing happens. The debugger cannot check whether you requested the breakpoint.

In addition, you do not need to request the breakpoint immediately on entry to the debugger. You can note the address and use it later to request the breakpoint when you want to use escape.

SYSTEM DEPENDENCIES

TSO: To use escape, you must run the SAS/C Debugger under TSO TEST.

1. Invoke the SAS/C Debugger using TSO TEST. (See Running the Debugger under TSO.) If you mistakenly invoke the debugger using the TSO CALL command, you cannot run your program under TEST.

2. Issue the TEST command GO to begin SAS/C Debugger execution. Read the ESCAPE message.

3. Press the attention key to return to TEST under TSO.

4. Request the breakpoint using the TEST command AT.

5. Issue the TEST command GO to return to the SAS/C Debugger. See the IBM publication OS/390 V2R9.0 TSO/E Command Reference SC28-1969 for more information about TSO TEST commands.

CMS: When you are running the SAS/C Debugger under CMS, use the debugger command system to issue a PER command to request a breakpoint. (Under VM/XA, the TRACE command is used instead of PER.) For example, if the breakpoint that you want to request is at 00D174, the following command requests the breakpoint:

system CP PER I R D174

Then, you can use escape to leave the SAS/C Debugger, examine your program under CP PER, and return to the SAS/C Debugger via the CP command BEGIN. See the IBM publication CP Command and Utility Reference SC24-5773 for more information about CP.

Register values: TSO and CMS: When you use escape to give control to TEST or PER, the register contents are the same as when the program transfers control to the debugger.

• For a normal line-number hook, register 1 points to the next instruction to be executed.

• For a return hook, register 14 contains the return address and register 15 contains the return value, if any, for integer and pointer type returns. Floating-point register 0 contains double return values.

• When control passes to the debugger due to a program check, register 1 addresses a copy of the EPIE generated by the system for the program check, which includes the register contents and PSW.

Modifying register contents while escaped under TEST or PER may not work and could potentially cause 0CX or other undesired effects. See return for information about setting RETURN values.

COMMAND CAN BE ISSUED FROM

PROFILE	no
configuration file	no
Source window prefix	none

SCOPE

The escape command is not affected by changes in scope.

RETURN CODES SET

none

SEE ALSO

system (CMS)

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Copyright © 2001 by SAS Institute Inc., Cary, NC, USA. All rights reserved.