HLASM - SVC = SuperVisor Call

The opcode of the SVC instruction is X'0A'.

Usage

  1. Invoke an operating system service or supervisor routine.

Arguments

  1. An integer number in the range 0-255 (in the instruction).

Function

  1. The processor generates an interrupt, which causes the processor to branch to the operating system's interrupt handling routine.
  2. The interrupt handling routine examines the SVC number and invokes the associated system service routine.
  3. What the invoked system service routine will do depends. Check the appropriate manual to find out the interface specifications.
  4. The SVC instruction does not change the condition code. However, when the processor handles the generated interrupt, a new PSW is loaded, which may contain a different condition code. To the program that issues the SVC instruction no change in condition code is noticeable.

Special Cases

  1. None.

Related Instructions

  1. None.

Hardware

  1. All hardware supports the SVC instruction.

Remarks

  1. Valid SVC numbers and their function are dependent upon the operating system and the operational environment. See our overview of SVC-routines which contains documented (current and historical) SVC-codes.

Examples

         YREGS                          * Define register names
         ...
         SVC   X'03'                    * Terminate current task (MVS)

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