At 08:09 -0400 on 05/01/2011, Shmuel Metz (Seymour J.) wrote about
Re: Mixing Auth and Non-Auth Modules:
In <[email protected]>, on 04/22/2011
at 11:12 PM, John McKown <[email protected]> said:
There are 4
types: 1, 2, 3, 4, and 6.
Types three and 4 are the same. Despite what the documentation says, a
type 3 SVC routine can do an XCTL.
That is because the difference between a T3 and T4 SVC is historical
(for OS/360). In the beginning if the SVC as one module it was T3. If
it was more than one, it was T4 (with the modules named IGCxxyyy -
YYY=SVC Number and XX being module number 00-99 [00 is the T3 SVC or
initial load of T4]). Once VS1/SVS/MVS replaced OS/360 there was no
need to load the SVC from SYS1.SVCLIB into a dedicated SVC area of
memory there was no need to distinguish between the single and
multiple module format and all T3s were treated as T4s (also a number
of T4s were mode into single module T3s at that time).
BTW: If I remember correctly, so far as the SVC table was concerned,
a T5 SVC as one that did not have an module defined for it (ie: Was
an undefined SVC). The table for these SVCs pointed at a common route
that handed the call by issuing a FXX (xx being the SVC number) ABEND.
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