MVS Jan 2005.p65 - CBT Tape

indicates whether the child process should run as a
subtask within the parent process address space or
whether the child process should run in its own address
space. The following _BPX_SHAREAS options are
supported:
– NO – the child process is created in a separate
address space. This is the default.
– REUSE – the child process is created as a subtask in
an existing task structure unless conditions exist that
force the child process to initiate a new task structure.
– MUST – the child process must run in the same
address space as the parent or the spawn request will
fail. Possible reasons for failure include:
o if the set UID or set GID of the spawned program
differs from the effective UID or the effective GID
of the parent
o the program to be run is APF authorized but the
parent is not
o the program to be run is unauthorized but the
parent program is APF authorized
o the parent process address space does not have
sufficient resources.
– YES – the child process will run as a subtask in the
same address space as the parent unless conditions
exist that force the creation of a child process address
space.
Spawn() initiates the requested program from its entry
point address. In contrast, with fork() the child process
program begins execution from the instruction following
the fork() instruction (not the entry point of the program)
and is always a copy of the parent process program.
Spawn() can be used to execute a completely different
program from that of the caller.
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