Specifying authorized path macroinstructions
The VTAM® authorized path macroinstructions can be executed asynchronously (OPTCD=ASY) or synchronously (OPTCD=SYN) under control of a service request block (SRB), or a task control block (TCB). Table 1 shows the coding requirements for VTAM authorized path, including the VTAM authorized path macroinstructions and the supervisor macroinstructions needed to execute the authorized path through VTAM. Consult the z/OS MVS Programming: Authorized Assembler Services Guide for information on coding the supervisor macroinstructions described in Table 1.
To use authorized path while running under a TCB, the authorized program, having put itself into supervisor state, specifies BRANCH=YES on any RPL-based macroinstruction that is to be executed using authorized path.
- Coding BRANCH=NO on a MODCB macroinstruction
- Referring to the field by using the IBM-supplied DSECT and turning it off with an assembler language instruction
- Coding BRANCH=NO on the subsequent macroinstruction that is not to use authorized path.
Authorized path is always used when an RPL-based macroinstruction is issued under the control of an SRB. A task identification and address space identification should be specified in the SRB as discussed in Task association; otherwise (RTNCD,FDB2)=(X'14',X'55') could result. One way to gain control under an SRB is for the authorized program, while running under a TCB, to specify an RPL exit routine when issuing (in supervisor state) an RPL-based macroinstruction that specifies BRANCH=YES. On entry to the RPL exit routine, the program is running under an SRB. Any RPL-based macroinstruction issued under an SRB is automatically executed using authorized path; BRANCH=YES need not be specified. An alternative way to create the SRB environment is to use the MVS™ SCHEDULE macroinstruction.
| Method of program execution (OPTCD=ASY or SYN operand specified on VTAM RPL and RPL-based macroinstructions) | ||
|---|---|---|
| Method of dispatching | Synchronous | Asynchronous |
| TCB |
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| SRB |
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