DCL_CTLFLAGS is a bit mask that alters default behavior for
certain DCL-related functions on a systemwide basis. However,
the default values satisfy the needs of most systems.
Bits 0 and 2 control the formulation of system-generated process
names for processes created using the SPAWN command or LIB$SPAWN
library routine. They are provided for compatibility with
behavior of prior OpenVMS versions. Note that you can eliminate
the use of system-generated names by supplying your own process
names.
Bit 1 controls the token size used by DCL.
Bit 3 controls the maximum number input parameters to command
procedure.
Bit 4 controls the the maximum length for an user name, for which
OpenVMS mail forwarding address is set.
DCL_CTLFLAGS bits are described in the following table.
Bit Description
Bit If clear (the default), the numeric portion of a system-
0 generated spawned process name is generated randomly. If
set, the numeric portion is generated sequentially starting
with sequence number 1.
The option of sequential generation is provided for
compatibility with prior versions of OpenVMS. However, this
choice can be very expensive in performance terms due to
the mechanism for finding the next available process name.
This mechanism attempts to create all process names beginning
with sequence number 1 until it finds one that is unused.
Random generation is the preferred choice because it
results in a very high probability of finding a unique
name on the first try.
Bit Controls the token size used by DCL. If clear (the
1 default), this bit instructs DCL to use the traditional
token size. A token cannot exceed 255 characters. If this
bit is set, extended tokens are used. Extended tokens are
4000 characters.
Note that if you turn on extended tokens, file
specifications can exceed 255 characters, which might
require larger structures for parsing file specifications.
Bit If clear (the default), the numeric portion of a system-
2 generated spawned process name has a maximum value of
65535. If set, the numeric portion of the name has a
maximum value of 255.
The option of a maximum of 255 is provided for
compatibility with prior OpenVMS versions when it was the
only choice. The larger maximum allows many more unique
spawned process names for a given process. For this reason,
it is the preferred choice. However, the larger maximum uses
two additional characters from the process name, which might
make it more difficult to identify users uniquely by looking
at their spawned process names. If this is an issue on your
system, setting bit 2 might be a better choice.
Bit If clear (the default), command procedure supports the
3 default eight optional parameters (that is, (P1,P2,...P8)).
If set, command procedure supports up to sixteen optional
parameters (that is, (P1,P2,...P16)). This is also
applicable when using the CALL command to transfer control
to a subroutine.
Bit This bit controls the the maximum length for an user name,
4 for which OpenVMS mail forwarding address is set. If clear
(the default), user name string length is set to a maximum
length of 31 characters. If set, user name string length is
set to a maximum of 255 characters.
Note: Once this bit is set, user name length is set to
maximum of 255 characters. Even if this bit is cleared,
the behavior remains unchanged, that is, supports user name
length of 255 characters, but there is no way to reset it
to 31 characters.
DCL_CTLFLAGS is a DYNAMIC parameter.
Note that changes to DCL_CTLFLAGS on a running system will only
affect processes created after the parameter is changed.