The IBM-supplied trap module (ISTRACZT) contains pretested
probes that you can use to capture data in places where a probe has
not been installed inside of VTAM®.
Before you begin
You need to obtain the VTAM module
name and offset in the VTAM module
from IBM® Service.
Procedure
Perform the following steps to install the trap program:
- Add an instruction to check the ATCFFST field in the ISTATCVT
control block. If ATCFFST is 0, VTAM FFST™ is not available.
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- Add an instruction to check the ATCRACZT field in the ISTATCVT
control block. If ATCRACZT is 0, the trap module is not available.
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- Add an instruction to call the trap module.
BALR R14,R15 -------- 05EF
DC X'0001' -------- 0001 (default)
A 2-byte field
containing X'0001' or X'0002' follows the BALR instruction.
A value of X'0001' issues the ISTRAC01 probe macro in VTAM with the SDUMP option. An
index value of X'0002' issues the ISTRAC01 probe macroinstruction
with the VTAM FFST minidump option. The ISTATCVT and the VIT
are included in the minidump output along with the VTAM module list, which contains the five significant
letters of a module name, its service level, and its address. Control
is returned to VTAM at the
address after the 2-byte index.
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Results
You know that you are done when you execute the program
and the trap is triggered, resulting in an SDUMP or FFST minidump (depending on the option chosen).
Notes: - The calling module must save GP register 7.
- The module is reentrant.
- AMODE is 24 or 31.
- All registers except 7 are saved and restored.
- The module is in LPALIB.
- If you are trying to invoke the trap module outside of the VTAM environment, you must take
the following steps:
- Follow the list shown above.
- Be in VTAM key (6).
- Be authorized.