xen-toolstack: command not found

Have You tried accessing the binary with the full path?

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/lib/xen-common/bin/xen-toolstack - from package: xen-utils-common

You may install the required package with command apt-get install {package}
Error in other languages:
xen-toolstack: bevel nie gevind nie
xen-toolstack: comandă negăsită
xen-toolstack: comando não encontrado
xen-toolstack: commande introuvable
xen-toolstack: command not found
xen-toolstack: käsku ei ole
xen-toolstack: không tìm thấy lệnh
xen-toolstack: komanda nerasta
xen-toolstack: Kommando nicht gefunden.
xen-toolstack: kommandot finns inte
xen-toolstack: komut yok
xen-toolstack: nie znaleziono polecenia
xen-toolstack: níor aimsíodh an t-ordú
xen-toolstack: no se encontró la orden
xen-toolstack: no s'ha trobat l'ordre
xen-toolstack: opdracht niet gevonden
xen-toolstack: parancs nem található
xen-toolstack: perintah tidak ditemukan
xen-toolstack: príkaz nenájdený
xen-toolstack: příkaz nenalezen
xen-toolstack: команда не найдена
xen-toolstack: командата не е открита
xen-toolstack: 命令找不到
xen-toolstack: コマンドが見つかりません