Specifications

Using Callable System Routines
10.3 System Services
Table 10–3 (Cont.) Summary of System Services
Service Function
DECdtm Services
$START_TRANS (and $START_TRANSW) Starts a new transaction (and wait).
Event Flag Services
$ASCEFC Associates a named common event flag cluster with a
process to execute the current image and to be assigned a
process-local cluster number for use with other event flag
services.
$CLREF Clears (sets to 0) an event flag in a local or common event
flag cluster.
$DACEFC Releases the calling process’s association with a common
event flag cluster.
$DLCEFC Marks a permanent common event flag cluster for deletion.
$READEF Returns the current status of all 32 event flags in a local
or common event flag cluster and indicates whether the
specified event flag is set or clear.
$SETEF Sets an event flag in a local or common event flag cluster.
$WAITFR Tests a specific event flag and returns immediately if the
flag is set. Otherwise, the process is placed in a wait state
until the event flag is set.
$WFLAND Allows a process to specify a set of event flags for which it
wants to wait.
$WFLOR Allows a process to specify a set of event flags for which it
wants to wait.
File Management Services
$FILESCAN Searches a string for a file specification and parses the
components of that file specification.
$SETDDIR Allows you to read and change the default directory string
for the process.
I/O Services
$ALLOC Allocates a device for exclusive use by a process and its
subprocesses.
$ASSIGN Provides a process with an I/O channel so that input
/output operations can be performed on a device, or
establishes a logical link with a remote node on a network.
$BRKTH (and $BRKTHW) Sends a message to one or more terminals (and wait).
$CANCEL Cancels all pending I/O requests on a specified channel.
$CREMBX Creates a virtual mailbox device named MBAn and assigns
an I/O channel to it.
$DALLOC Deallocates a previously allocated device.
$DASSGN Deassigns (releases) an I/O channel previously acquired
using the Assign I/O Channel ($ASSIGN) service.
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